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Groups > sci.math > #412942 > unrolled thread

The fundamental theorem of set theory is problematic

Started byDavid Petry <davidlpetry@gmail.com>
First post2018-05-11 11:20 -0700
Last post2018-05-17 12:29 -0700
Articles 20 on this page of 227 — 16 participants

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Contents

  The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-11 11:20 -0700
    Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-11 19:33 +0000
      Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-11 13:16 -0700
        Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-05-11 16:48 -0700
        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-11 18:31 -0700
          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-11 18:46 -0700
            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-11 18:49 -0700
              Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-12 00:59 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 02:20 -0700
              Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-12 12:43 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 14:09 -0700
          Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-12 12:40 -0700
            Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-12 20:48 +0000
              Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-12 14:50 -0700
                Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-13 01:00 +0000
                  Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-13 15:10 -0700
                    Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-14 17:33 +0000
                      Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-14 21:09 -0700
                        Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-15 19:19 +0000
                          Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-05-15 13:50 -0700
                          Re: The fundamental theorem of set theory is problematic "Shobe, Martin" <martin.shobe@yahoo.com> - 2018-05-15 21:34 -0500
                            Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-16 09:10 -0700
                            Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-16 09:15 -0700
                      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-15 05:33 -0700
              Re: The fundamental theorem of set theory is problematic Jim Burns <james.g.burns@att.net> - 2018-05-12 19:02 -0400
                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 01:38 -0700
                Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-14 21:40 -0700
                  Re: The fundamental theorem of set theory is problematic Jim Burns <james.g.burns@att.net> - 2018-05-15 05:22 -0400
              Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 01:31 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-13 03:51 -0700
                  Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 05:18 -0700
                    Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-13 06:59 -0700
                Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-13 11:02 +0000
                  Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 05:37 -0700
                    Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-13 21:57 +0100
                      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-14 04:44 -0700
                        Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-14 13:29 +0100
                          Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-14 07:42 -0700
                            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 09:36 -0700
                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 09:42 -0700
                              Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-14 18:29 +0100
                                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 12:03 -0700
                                  Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 12:06 -0700
                                    Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 12:10 -0700
                              Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-05-15 13:44 -0700
                            Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-14 18:16 +0100
                              Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-15 05:44 -0700
                        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-14 06:38 -0700
            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 17:58 -0700
              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 18:04 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 18:19 -0700
        Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-15 09:14 -0700
          Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-15 10:07 -0700
            Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-16 09:26 -0700
              Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-16 11:18 -0700
                Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-16 12:26 -0700
                  Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-16 14:06 -0700
                    Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-16 15:53 -0700
                      Re: The fundamental theorem of set theory is problematic Jim Burns <james.g.burns@att.net> - 2018-05-16 19:07 -0400
                        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 01:17 -0700
                          Re: The fundamental theorem of set theory is problematic Jim Burns <james.g.burns@att.net> - 2018-05-17 09:42 -0400
                  Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-16 17:40 -0700
          Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-15 11:06 -0700
      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-12 01:05 -0700
      Re: The fundamental theorem of set theory is problematic David Petry <davidlpetry@gmail.com> - 2018-05-12 12:57 -0700
        Re: The fundamental theorem of set theory is problematic Alan Mackenzie <acm@muc.de> - 2018-05-13 00:20 +0000
    Re: The fundamental theorem of set theory is problematic "Shobe, Martin" <martin.shobe@yahoo.com> - 2018-05-11 20:03 -0500
      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-12 00:59 -0700
      Re: The fundamental theorem of set theory is problematic Julio Di Egidio <julio@diegidio.name> - 2018-05-12 01:59 -0700
        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 02:55 -0700
          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 03:04 -0700
          Re: The fundamental theorem of set theory is problematic Julio Di Egidio <julio@diegidio.name> - 2018-05-12 03:06 -0700
            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 03:09 -0700
              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 03:13 -0700
                Re: The fundamental theorem of set theory is problematic Julio Di Egidio <julio@diegidio.name> - 2018-05-12 03:20 -0700
                  Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 03:28 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-12 03:24 -0700
    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-12 01:14 -0700
      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-13 09:07 -0700
        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 11:08 -0700
          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-13 12:05 -0700
            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-13 12:53 -0700
        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-15 11:02 -0700
          Re: The fundamental theorem of set theory is problematic j4n bur53 <janburse@fastmail.fm> - 2018-05-15 21:13 +0200
            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-16 11:30 -0700
              Re: The fundamental theorem of set theory is problematic Zeit Geist <Tucsondrew@me.com> - 2018-05-16 12:23 -0700
                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-16 14:00 -0700
                  Re: The fundamental theorem of set theory is problematic Zeit Geist <Tucsondrew@me.com> - 2018-05-16 16:18 -0700
                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-16 16:27 -0700
                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 05:01 -0700
                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-17 08:34 -0700
                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 09:34 -0700
                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-17 10:12 -0700
                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 10:57 -0700
                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 11:56 -0700
                                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 12:00 -0700
                                  Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 12:29 -0700
                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-17 13:38 -0700
                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-18 08:12 -0700
                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-18 12:23 -0700
                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-19 04:53 -0700
                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-19 07:21 -0700
                                        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-19 09:11 -0700
                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-20 03:20 -0700
                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-20 04:48 -0700
                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-20 05:19 -0700
                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-20 10:09 -0700
                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-20 13:26 -0700
                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-20 18:10 -0700
                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-21 06:05 -0700
                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-21 07:24 -0700
                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-21 08:59 -0700
                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-21 11:48 -0700
                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-22 05:45 -0700
                                                              Re: The fundamental theorem of set theory is problematic Python <python@python.invalid> - 2018-05-22 14:51 +0200
                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-22 06:31 -0700
                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-22 13:26 -0700
                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-22 14:22 -0700
                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 06:06 -0700
                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-23 07:19 -0700
                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 11:56 -0700
                                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-23 12:08 -0700
                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 13:22 -0700
                                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-23 18:11 -0700
                                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-24 02:47 -0700
                                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-24 06:00 -0700
                                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-24 07:43 -0700
                                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-24 08:10 -0700
                                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-24 09:37 -0700
                                                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-24 09:45 -0700
                                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-25 09:05 -0700
                                                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-25 11:09 -0700
                                                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-25 15:26 -0700
                                                                                                  Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-25 23:14 -0700
                                                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-26 03:23 -0700
                                                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-26 06:37 -0700
                                                                                                      Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-26 06:50 -0700
                                                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-26 07:30 -0700
                                                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-26 08:39 -0700
                                                                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-26 09:15 -0700
                                                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-27 05:37 -0700
                                                                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-27 08:58 -0700
                                                                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-28 03:53 -0700
                                                                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-28 05:04 -0700
                                                                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-28 05:10 -0700
                                                                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-28 05:19 -0700
                                                                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-29 04:53 -0700
                                                                                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-29 06:22 -0700
                                                                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-29 06:36 -0700
                                                                                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-29 07:12 -0700
                                                                                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-29 08:35 -0700
                                                                                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-29 08:52 -0700
                                                                                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-30 04:25 -0700
                                                                                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-30 04:50 -0700
                                                                                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-31 06:17 -0700
                                                                                                                                          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-31 07:05 -0700
                                                                                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-31 09:53 -0700
                                                                                                                                              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-31 11:47 -0700
                                                                                                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-06-01 03:58 -0700
                                                                                                                                                  Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-06-01 05:07 -0700
                                                                                                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-06-01 05:24 -0700
                                                                                                                                                      Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-06-01 06:27 -0700
                                                                                                                                                        Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-06-01 10:21 -0700
                                                                                                                                                          Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-06-02 14:04 -0700
                                                                                                                                                            Re: The fundamental theorem of set theory is problematic "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-06-02 16:27 -0700
                                                                                                                                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-06-02 07:23 -0700
                                                                                                                                                          Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-06-04 00:11 -0700
                                                                                                              Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-27 23:12 -0700
                                                                          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-23 12:49 -0700
                                                                            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-23 12:51 -0700
                                                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 13:24 -0700
                                                                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-24 02:09 -0700
                                                              Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-22 19:09 +0100
                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-22 13:29 -0700
                                                              Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-23 22:32 -0700
                                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-24 03:57 -0700
                                                                  Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-24 04:48 -0700
                                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-24 07:29 -0700
                                                                      Re: The fundamental theorem of set theory is problematic Python <python@python.invalid> - 2018-05-24 16:39 +0200
                              Re: The fundamental theorem of set theory is problematic Python <python@python.invalid> - 2018-05-18 01:19 +0200
                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-18 08:14 -0700
                                  Re: The fundamental theorem of set theory is problematic Python <python@python.invalid> - 2018-05-18 17:31 +0200
                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-18 10:09 -0700
                                      Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-18 10:53 -0700
                                      Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 13:54 -0700
                                        Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 13:55 -0700
                                          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 14:09 -0700
                                            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 14:19 -0700
                                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 14:23 -0700
                                                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-18 14:37 -0700
                                      Re: The fundamental theorem of set theory is problematic Zeit Geist <Tucsondrew@me.com> - 2018-05-18 14:33 -0700
                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-19 04:58 -0700
                                          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-19 05:28 -0700
                                            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-19 05:34 -0700
                                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-19 05:36 -0700
                                                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-19 05:46 -0700
                                          Re: The fundamental theorem of set theory is problematic Zeit Geist <Tucsondrew@me.com> - 2018-05-19 09:00 -0700
                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-20 03:21 -0700
                                      Re: The fundamental theorem of set theory is problematic Python <python@python.invalid> - 2018-05-19 02:01 +0200
                                      Re: The fundamental theorem of set theory is problematic Alan Smaill <smaill@SPAMinf.ed.ac.uk> - 2018-05-21 16:40 +0100
                                        Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-21 09:06 -0700
                                          Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-21 13:52 -0700
                                            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-22 05:45 -0700
                                              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-22 08:27 -0700
                                                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-22 13:29 -0700
                                                  Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-22 13:43 -0700
                                                    Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-22 13:52 -0700
                                                      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 06:06 -0700
                                                  Re: The fundamental theorem of set theory is problematic Zeit Geist <Tucsondrew@me.com> - 2018-05-22 17:30 -0700
                                                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-23 06:06 -0700
          Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-15 17:14 -0700
            Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-16 11:26 -0700
              Re: The fundamental theorem of set theory is problematic wpihughes@gmail.com - 2018-05-16 16:35 -0700
                Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 05:03 -0700
                  Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-17 05:33 -0700
                    Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 09:31 -0700
    Re: The fundamental theorem of set theory is problematic Sergio <invalid@invalid.com> - 2018-05-13 12:40 -0500
    Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-13 22:36 -0700
      Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-14 04:49 -0700
        Re: The fundamental theorem of set theory is problematic Zelos Malum <zelos.malum@gmail.com> - 2018-05-17 01:34 -0700
          Re: The fundamental theorem of set theory is problematic WM <wolfgang.mueckenheim@hs-augsburg.de> - 2018-05-17 05:08 -0700
            Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 10:03 -0700
              Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 10:06 -0700
                Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 10:19 -0700
                  Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 10:26 -0700
                    Re: The fundamental theorem of set theory is problematic bursejan@gmail.com - 2018-05-17 10:30 -0700
                  Re: The fundamental theorem of set theory is problematic FredJeffries <fredjeffries@gmail.com> - 2018-05-17 12:29 -0700

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#412942 — The fundamental theorem of set theory is problematic

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-11 11:20 -0700
SubjectThe fundamental theorem of set theory is problematic
Message-ID<92d7be26-4688-49f3-8875-b54aae5cd3ed@googlegroups.com>

The essence of mathematics is proof.  The idea behind proof is that if we believe we have proved some assertion, then we must also believe that everyone has no choice but to believe that the assertion is actually true.  And consistent with the idea that the essence of mathematics is proof, is the idea that the domain of discourse for mathematics is the things that are provably well-defined.

So now let's look at the fundamental theorem of set theory (Cantor's theorem).

If we have a provably well-defined list of provably well-defined real numbers (so that every digit of every real number in the list can be computed), then the diagonal argument gives us a provably well-defined real number that is not in that list.  So if we start with the premiss that the domain of discourse for mathematics is the things that are provably well-defined, then the diagonal argument most certainly does not prove to us that there must exist anything outside of that domain.  At the same time, the domain of discourse cannot be larger than "countable", since proofs are objects in a language, and languages are countable.  The conclusion being that there is no reason to think we are compelled to believe in the existence of uncountable sets, which contradicts what Cantor's theorem says, and furthermore, there is good reason to say that Cantor's theorem is false.

Note that I'm not claiming that set theory is inconsistent as a game consisting of symbols and rules for manipulating strings of those symbols, as long as we recognize that the symbols have no meaning, and the strings of symbols have no connection to truth and reality.

The argument I just presented for not accepting set theory as part of mathematics has been around right from the start of set theory.  I believe that Julius Konig was the first to present that argument (or some variation of it).  The fact that many first rate mathematicians do not believe that Cantor's formal proof proves that his theorem is actually true, should be seen as justification for believing that set theory is not part of mathematics: mathematics is all about things we have no choice but to believe are actually true.

Mathematics has important connections to real life.  Real life is not just a game.  Set theory is nothing but a game.  It is not mathematics.

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#412944

FromAlan Mackenzie <acm@muc.de>
Date2018-05-11 19:33 +0000
Message-ID<pd4r6o$228$1@news.muc.de>
In reply to#412942
David Petry <davidlpetry@gmail.com> wrote:


> The essence of mathematics is proof.  The idea behind proof is that if
> we believe we have proved some assertion, then we must also believe
> that everyone has no choice but to believe that the assertion is
> actually true.  And consistent with the idea that the essence of
> mathematics is proof, is the idea that the domain of discourse for
> mathematics is the things that are provably well-defined.

This last is false.  What maths discusses also includes things which
haven't been proven, and indeed can't be proven.  For exampe proof by
contradiction discusses such things.

> So now let's look at the fundamental theorem of set theory (Cantor's
> theorem).

> If we have a provably well-defined list of provably well-defined real
> numbers (so that every digit of every real number in the list can be
> computed), ....

Is that your definition of "provably well-defined"?  If so, I suggest it
is not a useful definition.  "Every real number between 0 and 1 which
isn't rational" is provably well defined, by any reasonable
interpretation of that phrase.

> .... then the diagonal argument gives us a provably well-defined real
> number that is not in that list.

Yes, demonstrating that the list cannot have been complete in a well
understood sense.

> So if we start with the premiss that the domain of discourse for
> mathematics is the things that are provably well-defined, then the
> diagonal argument most certainly does not prove to us that there must
> exist anything outside of that domain.

That's not what the diagonal argument proves.  This is that a supposed
countable list of all real numbers cannot exist.  Hence the real numbers
are not countable.

> At the same time, the domain of discourse cannot be larger than
> "countable", since proofs are objects in a language, and languages are
> countable.

You're confusing two distinct meanings of "domain of discourse": (i) the
domain of proofs; this is indeed countable; (ii) The entities these
proofs deal with, which need not be countable.

> .... The conclusion being that there is no reason to think we are
> compelled to believe in the existence of uncountable sets, ..... 

If you accept the axiom of completion (which distinguishes the real
numbers from countable subsets of them), you are compelled to believe in
uncountable sets.

> .... which contradicts what Cantor's theorem says, and furthermore,
> there is good reason to say that Cantor's theorem is false.

Cantor rigorously demonstrated the existence of non-countable sets, based
only on the representation of numbers as arbitrary decimal expansions.
If you wanted this theorem to be false, you'd have to somehow do away
with decimal expansions of numbers.  But why would you want this?

> Note that I'm not claiming that set theory is inconsistent as a game
> consisting of symbols and rules for manipulating strings of those
> symbols, as long as we recognize that the symbols have no meaning, and
> the strings of symbols have no connection to truth and reality.

You could say the same about any mathematical argument.  As for truth and
reality, that's more the domain of philosophers than mathematicians.

> The argument I just presented for not accepting set theory as part of
> mathematics has been around right from the start of set theory.  I
> believe that Julius Konig was the first to present that argument (or
> some variation of it).  The fact that many first rate mathematicians do
> not believe that Cantor's formal proof ....

Fact?  That assertion is screaming out for a citation.  As far as I am
aware, Cantor's arguments are now universally accepted by mathematicians.

> .... proves that his theorem is actually true, should be seen as
> justification for believing that set theory is not part of mathematics:
> mathematics is all about things we have no choice but to believe are
> actually true.

Fermat's Last Theorem has been part of maths for several hundred years,
and up until ~20 years ago one had the choice to believe it or not.  I
think you have mis-characterised maths.  There are many mathematical
topics which one has the choice to believe or not (areas of research).
At another level you can chose to "believe" (or not) the axiom of choice,
for example.  You'll get somewhat different systems of maths depending on
your choice.

> Mathematics has important connections to real life.  Real life is not
> just a game.  Set theory is nothing but a game.  It is not mathematics.

Set theory is part of mathematics.  Not all of maths has important
connections with real life (whatever that might be).

-- 
Alan Mackenzie (Nuremberg, Germany).

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#412946

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-11 13:16 -0700
Message-ID<be32e459-cdae-422f-9e2b-05abebd2e0a8@googlegroups.com>
In reply to#412944
> As far as I am 
> aware, Cantor's arguments are now universally accepted by mathematicians. 

"Set theory is based on polite lies, things we agree on even though we know they're not true"  --William Thurston

for example.

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#412950

From"Ross A. Finlayson" <ross.finlayson@gmail.com>
Date2018-05-11 16:48 -0700
Message-ID<61633987-0bd1-4a20-b12a-0e1a20688da3@googlegroups.com>
In reply to#412946
Seems as easy to fabricate a usual 
"lesser" model of the reals as via 
EF and line continuity (sweep 
principle of a continuum) for a 
certain countable model of the 
linear continuum, then tack the 
moderb mathematic's abstract algebra's 
countable character of the real 
analysis onto (and after) that.

Then the reals of the complete ordered 
field are uncountable but there's also 
a countable model of the reals.

(And for some that's rather the 
more fundamental.)

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#412953

Frombursejan@gmail.com
Date2018-05-11 18:31 -0700
Message-ID<37464760-151e-486d-a8a6-a0cfda1df2ff@googlegroups.com>
In reply to#412946
Maybe set theory should start with the young.

"Students in college mathematics courses 
are unresponsive. They are afraid to 
speculate and afraid to reach into 
themselves for ideas. When one visits 
classrooms at different grade levels, 
one sees a dramatic decline in liveliness 
and spontaneity with age. One gets the 
impression that the natural interest and 
curiosity of young children in mathematics 
has been weeded out."
--William Thurston

Am Freitag, 11. Mai 2018 22:16:23 UTC+2 schrieb David Petry:
> > As far as I am 
> > aware, Cantor's arguments are now universally accepted by mathematicians. 
> 
> "Set theory is based on polite lies, things we agree on even though we know they're not true"  --William Thurston
> 
> for example.

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#412954

Frombursejan@gmail.com
Date2018-05-11 18:46 -0700
Message-ID<44cf53ec-c53c-4516-92eb-efc7acf973b8@googlegroups.com>
In reply to#412953
On the other hand, what does "do" mean here:

"G ̈odel’s incompleteness theorem implies that 
there can be no formal system that is consistent, 
yet powerful enough to serve as a basis for all 
of the mathematics that we do."
--William Thurston

Had William Thurston the idea that mathematics
can be communicated above formal systems and
transcending what formal system can "do", by
their own "doing". How is this "done"?

Am Samstag, 12. Mai 2018 03:31:34 UTC+2 schrieb burs...@gmail.com:
> Maybe set theory should start with the young.
> 
> "Students in college mathematics courses 
> are unresponsive. They are afraid to 
> speculate and afraid to reach into 
> themselves for ideas. When one visits 
> classrooms at different grade levels, 
> one sees a dramatic decline in liveliness 
> and spontaneity with age. One gets the 
> impression that the natural interest and 
> curiosity of young children in mathematics 
> has been weeded out."
> --William Thurston
> 
> Am Freitag, 11. Mai 2018 22:16:23 UTC+2 schrieb David Petry:
> > > As far as I am 
> > > aware, Cantor's arguments are now universally accepted by mathematicians. 
> > 
> > "Set theory is based on polite lies, things we agree on even though we know they're not true"  --William Thurston
> > 
> > for example.

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#412955

Frombursejan@gmail.com
Date2018-05-11 18:49 -0700
Message-ID<4fafb0ef-fde0-4632-b8c1-57312c353471@googlegroups.com>
In reply to#412954
Either William Thurston was a complete moron
or he had a secret that he didnt tell anybody.

Am Samstag, 12. Mai 2018 03:46:35 UTC+2 schrieb burs...@gmail.com:
> On the other hand, what does "do" mean here:
> 
> "G ̈odel’s incompleteness theorem implies that 
> there can be no formal system that is consistent, 
> yet powerful enough to serve as a basis for all 
> of the mathematics that we do."
> --William Thurston
> 
> Had William Thurston the idea that mathematics
> can be communicated above formal systems and
> transcending what formal system can "do", by
> their own "doing". How is this "done"?
> 
> Am Samstag, 12. Mai 2018 03:31:34 UTC+2 schrieb burs...@gmail.com:
> > Maybe set theory should start with the young.
> > 
> > "Students in college mathematics courses 
> > are unresponsive. They are afraid to 
> > speculate and afraid to reach into 
> > themselves for ideas. When one visits 
> > classrooms at different grade levels, 
> > one sees a dramatic decline in liveliness 
> > and spontaneity with age. One gets the 
> > impression that the natural interest and 
> > curiosity of young children in mathematics 
> > has been weeded out."
> > --William Thurston
> > 
> > Am Freitag, 11. Mai 2018 22:16:23 UTC+2 schrieb David Petry:
> > > > As far as I am 
> > > > aware, Cantor's arguments are now universally accepted by mathematicians. 
> > > 
> > > "Set theory is based on polite lies, things we agree on even though we know they're not true"  --William Thurston
> > > 
> > > for example.

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#412961

FromWM <wolfgang.mueckenheim@hs-augsburg.de>
Date2018-05-12 00:59 -0700
Message-ID<f8a5c513-5083-458b-9f0a-e65ad70c308b@googlegroups.com>
In reply to#412955
Am Samstag, 12. Mai 2018 03:49:20 UTC+2 schrieb burs...@gmail.com:
> Either William Thurston was a complete moron

or Burse.

Regards, WM

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#412967

Frombursejan@gmail.com
Date2018-05-12 02:20 -0700
Message-ID<fbe3e659-6f79-45f2-8bae-e51292cd15e8@googlegroups.com>
In reply to#412961
Here we see how old, WM, cannot grip irrational numbers,
maybe set theory should start with the young, when
old, its too late. Yes, usual proof is that |R|>|N|,
there is a paper by Cantor with comment by Zermelo,

very famous paper, that shows that. Maybe the
notion potential infinite makes an exception here,
but this notion is not found in ZFC. So if R and N
are sets, then there is no bijection f : N -> R.

Am Samstag, 12. Mai 2018 09:59:43 UTC+2 schrieb WM:
> Am Samstag, 12. Mai 2018 03:49:20 UTC+2 schrieb burs...@gmail.com:
> > Either William Thurston was a complete moron
> 
> or Burse.
> 
> Regards, WM

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#412996

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-12 12:43 -0700
Message-ID<f86ce98c-1d40-4d44-a37f-d101cc5c7b5f@googlegroups.com>
In reply to#412955
> Either William Thurston was a complete moron 
> or he had a secret that he didnt tell anybody. 

Or maybe he tried hard to tell everybody the "secret",  but people won't listen.

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#413000

Frombursejan@gmail.com
Date2018-05-12 14:09 -0700
Message-ID<f1dc5f78-603c-47dd-90e2-77bdb2f12a44@googlegroups.com>
In reply to#412996
You mean like Witgensteins understanding of Gödel?

"Since the publication of Wittgenstein's Nachlass 
in 2000, a series of papers in philosophy have 
sought to evaluate whether the original criticism 
of Wittgenstein's remarks was justified. Floyd 
and Putnam (2000) argue that Wittgenstein had a 
more complete understanding of the incompleteness 
theorem than was previously assumed."
https://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems#Wittgenstein

Ha Ha, " ... more complete ... of the incompletness ..."
sounds very funny.

Maybe we can simply conclude William Thurston didn't
understand the theorem, maybe not exactly in the same 
fashion like Wittgenstein:

"It is clear from the passages you cite that 
Wittgenstein did not understand [the first 
incompleteness theorem] (or pretended not to 
understand it). He interpreted it as a kind of 
logical paradox, while in fact is just the 
opposite, namely a mathematical theorem within 
an absolutely uncontroversial part of mathematics 
(finitary number theory or combinatorics)." 
(Wang 1996:179)

I don't know. I depends what William Thurston 
exactly meant by "do"? AP brain farto went 
berserk with a crazy post about God, IS and 
DOES a few hours ago. Ha Ha laughing my ass off.

https://groups.google.com/forum/#!topic/sci.math/sUR7ftnGeFU

Maybe his kitchen sink exploded because of
the many conic sections that were oval,
but not ellipse. 

Am Samstag, 12. Mai 2018 21:43:51 UTC+2 schrieb David Petry:
> > Either William Thurston was a complete moron 
> > or he had a secret that he didnt tell anybody. 
> 
> Or maybe he tried hard to tell everybody the "secret",  but people won't listen.

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#412995

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-12 12:40 -0700
Message-ID<2e2bf3e4-92b6-45a9-9606-8d58a7e39c48@googlegroups.com>
In reply to#412953
> Maybe set theory should start with the young. 
>
> "Students in college mathematics courses 
> are unresponsive. They are afraid to 
> speculate and afraid to reach into 
> themselves for ideas. When one visits 
> classrooms at different grade levels, 
> one sees a dramatic decline in liveliness 
> and spontaneity with age. One gets the 
> impression that the natural interest and 
> curiosity of young children in mathematics 
> has been weeded out." 
> --William Thurston 


That's a very interesting quote from Thurston.  Thank you for posting it.  I'd like to encourage people to read that two or three times.


"Students in college mathematics courses ... are afraid to ... reach into themselves for ideas."


One of the ideas that I have been promoting over the years is that mathematics comes from introspection.  It comes from seeking to understand how we reason about the real world.  This should include seeking to understand how we distinguish truth from fiction, and how we distinguish reality from fantasy.  And then mathematics could be defined as a formalization of that undertanding of ourselves.  And then, for example, it would be seen that the idea of falsifiability, which scientists use to distinguish science from pseudoscience, can and should be formalized and integrated into the foundations of mathematics, where it could be used to distinguish between mathematics and pseudo-mathematics.  And set theory would be seen at pseudo-mathematics.

If we start teaching set theory to the very young, it will only make the problems that Thurston delineates much worse.

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#412999

FromAlan Mackenzie <acm@muc.de>
Date2018-05-12 20:48 +0000
Message-ID<pd7jur$nh4$1@news.muc.de>
In reply to#412995
David Petry <davidlpetry@gmail.com> wrote:
>> Maybe set theory should start with the young. 
>>
>> "Students in college mathematics courses 
>> are unresponsive. They are afraid to 
>> speculate and afraid to reach into 
>> themselves for ideas. When one visits 
>> classrooms at different grade levels, 
>> one sees a dramatic decline in liveliness 
>> and spontaneity with age. One gets the 
>> impression that the natural interest and 
>> curiosity of young children in mathematics 
>> has been weeded out." 
>> --William Thurston 


> That's a very interesting quote from Thurston.  Thank you for posting
> it.  I'd like to encourage people to read that two or three times.


> "Students in college mathematics courses ... are afraid to ... reach
> into themselves for ideas."


> One of the ideas that I have been promoting over the years is that
> mathematics comes from introspection.  It comes from seeking to
> understand how we reason about the real world.  This should include
> seeking to understand how we distinguish truth from fiction, and how we
> distinguish reality from fantasy.  And then mathematics could be
> defined as a formalization of that undertanding of ourselves.  And
> then, for example, it would be seen that the idea of falsifiability,
> which scientists use to distinguish science from pseudoscience, can and
> should be formalized and integrated into the foundations of
> mathematics, where it could be used to distinguish between mathematics
> and pseudo-mathematics.  And set theory would be seen as
> pseudo-mathematics.

This last sentence is garbage.  Dangerous garbage.  It's like arguing to
impressionable youngsters that the Earth is flat.  Your opening post to
this thread strongly suggests you do not understand Cantor's proof - that
you do not understand proof by contradiction at all.  If so, then
anything you opine about maths is suspect.

Set theory is established mathematics, just as a round Earth is
established geography, evolution is established biology, and
electromagnetism is established physics.  To pretend otherwise is to act
as a crank, and to spread ignorance.

> If we start teaching set theory to the very young, it will only make
> the problems that Thurston delineates much worse.

I agree, but not for the reasons you would put forward.  Set theory as
taught to the very young consists of putting intersecting circles on a
blackboard with small numbers of objects in each, and announcing the
definitions of union and intersection.  This is pointless to the
children, and is dull, dull, dull.

Set theory only becomes interesting with infinite sets.  Young children
lack the intellectual development to cope with the infinite.  Set theory
should only be taught to older age groups, when they are ready for it.

-- 
Alan Mackenzie (Nuremberg, Germany).

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#413002

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-12 14:50 -0700
Message-ID<ac275d5b-5a14-47d9-9f0f-b029e83712b4@googlegroups.com>
In reply to#412999
Alan Mackenzie wrote:

> Set theory is established mathematics, just as a round Earth is 
> established geography, ...

So now we see your true colors -- you're an antidisestablishmentarianist!  You're saying that whatever has been "established", cannot possibly in a million years be disestablished!  I've been waiting so long for a chance to use that word!

All kidding aside, I am suggesting that reasoning about the foundations of mathematics requires non-monotonic reasoning.  I'm suggesting that we start with the idea that mathematics is a framework for reasoning about the real world, and then as we gain a better understanding of what "real world" even means, and a better understanding of how we reason about the real world, we must be willing to clear out the "deadwood" from mathematics when it has no relevance for reasoning about the real world, even if that deadwood is believed to be "established".

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#413009

FromAlan Mackenzie <acm@muc.de>
Date2018-05-13 01:00 +0000
Message-ID<pd82mv$656$1@news.muc.de>
In reply to#413002
David Petry <davidlpetry@gmail.com> wrote:

> Alan Mackenzie wrote:

>> Set theory is established mathematics, just as a round Earth is
>> established geography, ...

> So now we see your true colors -- you're an
> antidisestablishmentarianist!  You're saying that whatever has been
> "established", cannot possibly in a million years be disestablished!
> I've been waiting so long for a chance to use that word!

Not at all.  Newtonian mechanics, a well established theory, was
displaced by Einstein's relativity.  Einstein understood Newtonian
mechanics very well, and enhanced it to make it fit new observations.  I
am all in favour of the progress and spread of knowledge.  What I'm not
in favour of is the spreading of falsehoods by ignorant cranks.

You are trying to smear set theory largely because you don't understand
it.  Let me repeat, because you ignored it in my last post: there is no
sign in the post with which you opened this thread that you understand
Cantor's proof, in particular, or proof by contradiction in general.
This is so basic to mathematics, that lack of this understanding renders
your opinions about maths inconsequential.

> All kidding aside, I am suggesting that reasoning about the foundations
> of mathematics requires non-monotonic reasoning.  I'm suggesting that
> we start with the idea that mathematics is a framework for reasoning
> about the real world, and then as we gain a better understanding of
> what "real world" even means, and a better understanding of how we
> reason about the real world, we must be willing to clear out the
> "deadwood" from mathematics when it has no relevance for reasoning
> about the real world, even if that deadwood is believed to be
> "established".

I am suggesting you lack the background to make any such pronouncements.
Aside from that, much of maths has little or no connection with the "real
world" and that is just fine - take John Wiles's proof of Fermat's last
theorem as an example - yet it is a triumph of human endeavour, fully
comparable with the creation of great music or visual art.

Anyway, "deadwood" does get cleared from maths, by people moving on from
it to other things.  How many people still study Euclidean geometry or
quaternions, for example?  But the study of modular forms, once old
fashioned, got a kick from the said John Wiles's and colleagues'
investigations into FLT.

-- 
Alan Mackenzie (Nuremberg, Germany).

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#413041

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-13 15:10 -0700
Message-ID<59359449-8767-4235-90ae-184881394e91@googlegroups.com>
In reply to#413009
Alan Mackenzie wrote:

> there is no 
> sign in the post with which you opened this thread that you understand 
> Cantor's proof, in particular, or proof by contradiction in general. 


Since you've been rather rude to me, I'm going to offer you some advice.

Learn something about constructivism.  Try to understand why the constructivists reject proof by contradiction.  The Wikipedia is a good place to start.

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#413087

FromAlan Mackenzie <acm@muc.de>
Date2018-05-14 17:33 +0000
Message-ID<pdch8h$t87$1@news.muc.de>
In reply to#413041
David Petry <davidlpetry@gmail.com> wrote:

> Alan Mackenzie wrote:

>> there is no 
>> sign in the post with which you opened this thread that you understand 
>> Cantor's proof, in particular, or proof by contradiction in general. 


> Since you've been rather rude to me, .....

Toughen up, this is Usenet.  Your opening post in this thread made
outrageous suggestions (just, as an example, that a part of standard
maths isn't maths at all), and what you call rudeness is what you
intended to provoke.

At one point you were talking about manipulating the individual elements
of a list that does not, and cannot exist.  You introduce this impossible
list by saying "if we have a provably well-defined list of provable
well-defined real numbers ....".  You begin by assuming the converse of
what Cantor proves.  This doesn't suggest understanding, or a desire for
clarity.

Please settle the matter you quoted me writing.  Do you understand
Cantor's proof?  Do you understand proof by contradiction?  I will accept
your (straightforward) answers.

> .... I'm going to offer you some advice.

> Learn something about constructivism.  Try to understand why the
> constructivists reject proof by contradiction.  The Wikipedia is a good
> place to start.

I've skimmed the article in the English wikipedia on Constructivism.  I
don't find it, as yet, an attractive philosophy.  It may surprise you to
learn that I don't find the theory of transfinite numbers attractive
either, but at least I'm not about to try to demote rigorous mathematical
results to the realm of "non-mathematics".

It strikes me, as a novice to the topic, that constructive mathematics is
going to have difficulty proving theorems of the form "There does not
exist ...." or "There exist an infinite number of ....", but no doubt
that would become clearer from more intense study.

Also, it seems constructive mathematics is going to be less rich, and
less full than standard mathematics.  To give up proof by contradiction
would be to leave easily proven theorems provable only with great
difficulty, or possibly not at all.  All for what?

-- 
Alan Mackenzie (Nuremberg, Germany).

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#413101

FromDavid Petry <davidlpetry@gmail.com>
Date2018-05-14 21:09 -0700
Message-ID<8ed48cac-6165-478d-83e9-c3df88d1e5bb@googlegroups.com>
In reply to#413087
Alan Mackenzie wrote:

> I've skimmed the article in the English wikipedia on Constructivism.  I 
> don't find it, as yet, an attractive philosophy.  


The basic idea behind constructivism is that the logic and reasoning used by the constructivists is much closer to the reasoning used in science and technology than the logic used in classical pure mathematics.

In particular, the reasoning used in science and technology would never lead to the conclusion that there exists a super-infinite universe lying beyond the potentially infinite universe that science and technology deals with.

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#413132

FromAlan Mackenzie <acm@muc.de>
Date2018-05-15 19:19 +0000
Message-ID<pdfbs0$2oat$1@news.muc.de>
In reply to#413101
David Petry <davidlpetry@gmail.com> wrote:

> Alan Mackenzie wrote:

>> I've skimmed the article in the English wikipedia on Constructivism.
>> I don't find it, as yet, an attractive philosophy.  


> The basic idea behind constructivism is that the logic and reasoning
> used by the constructivists is much closer to the reasoning used in
> science and technology than the logic used in classical pure
> mathematics.

OK.  That doesn't make me like it, though.

> In particular, the reasoning used in science and technology would never
> lead to the conclusion that there exists a super-infinite universe
> lying beyond the potentially infinite universe that science and
> technology deals with.

That's a self-referential statement that appears more meaningful than it
is.  It says "science ... would never ... beyond the potentially infinite
univers dealt with by science".  In fact it says nothing.

The Super-infinite universe is the subject of earnest scientific
research: it goes by the name "Multiverse".  Who knows, maybe the
topology of this postulated multiverse is modelled by the familiar
transfinite numbers somehow.

-- 
Alan Mackenzie (Nuremberg, Germany).

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#413138

From"Ross A. Finlayson" <ross.finlayson@gmail.com>
Date2018-05-15 13:50 -0700
Message-ID<821cdd90-e7fe-4402-bb43-0a36d2c3eeaa@googlegroups.com>
In reply to#413132
On Tuesday, May 15, 2018 at 12:19:34 PM UTC-7, Alan Mackenzie wrote:
> David Petry <davidlpetry@gmail.com> wrote:
> 
> > Alan Mackenzie wrote:
> 
> >> I've skimmed the article in the English wikipedia on Constructivism.
> >> I don't find it, as yet, an attractive philosophy.  
> 
> 
> > The basic idea behind constructivism is that the logic and reasoning
> > used by the constructivists is much closer to the reasoning used in
> > science and technology than the logic used in classical pure
> > mathematics.
> 
> OK.  That doesn't make me like it, though.
> 
> > In particular, the reasoning used in science and technology would never
> > lead to the conclusion that there exists a super-infinite universe
> > lying beyond the potentially infinite universe that science and
> > technology deals with.
> 
> That's a self-referential statement that appears more meaningful than it
> is.  It says "science ... would never ... beyond the potentially infinite
> univers dealt with by science".  In fact it says nothing.
> 
> The Super-infinite universe is the subject of earnest scientific
> research: it goes by the name "Multiverse".  Who knows, maybe the
> topology of this postulated multiverse is modelled by the familiar
> transfinite numbers somehow.
> 
> -- 
> Alan Mackenzie (Nuremberg, Germany).

Many these days are putting down the Multiple Worlds Interpretation 
because they'd all be in one again and that's just the one (eg that 
the Pauli versus Schroedinger or rather Heisenberg find that the 
objects do have their position and momentum, that measurement is 
in effect as the measurement or observer effect, rather mechanically 
or as courtesy energy and configuration of experiment).

That the universe contains itself or for example that the universe 
of physical objects (eg, particles, waves, fields, or voids) as 
mathematical objects sees that the universe is infinite and full 
of those has also that it's an example of "Cantor's paradox" or 
that it's its own powerset and contains itself.

So, the "trans-finite" is in a sense only as familiar as the 
polynomial or power series, and, there's quite all the rest 
of the "infinite" that the trans-finite is only a tiny part.

Let's keep in mind that physics as science today and theory 
has conservation and symmetry as utmost principle.

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