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Re: Why is model theory needed?

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Subject Re: Why is model theory needed?
From Dan Christensen <Dan_Christensen@sympatico.ca>
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On Wednesday, May 31, 2023 at 2:50:58 PM UTC-4, Ross Finlayson wrote:
> On Wednesday, May 31, 2023 at 8:39:03 AM UTC-7, Dan Christensen wrote: 
> > On Wednesday, May 31, 2023 at 11:28:54 AM UTC-4, Ross Finlayson wrote: 
> > > On Wednesday, May 31, 2023 at 8:21:19 AM UTC-7, Dan Christensen wrote: 
> > > > On Wednesday, May 31, 2023 at 5:09:14 AM UTC-4, Mild Shock wrote: 
> > > > 
> > > > > Dan Christensens proof still uses a lot of double negation 
> > > > > removal, is not constructive as it is presented currently: 
> > > > > http://www.dcproof.com/UniversalSet.htm 
> > > > Double negation removal is a legitimate method of proof accepted by the vast majority of mathematicians. Must be frustrating as hell for you, Mr. Collapse. (Hee, hee!) 
> > > > Dan 
> > > > 
> > > > Download my DC Proof 2.0 freeware at http://www.dcproof.com 
> > > > Visit my Math Blog at http://www.dcproof.wordpress.com 
> > > So are a bunch of derivation rules in the contrapositive about 
> > > implications, the direct variety: legitimate derivation rules, 
> > > that applied to "material implications": result garbage. 
> > > 
> > A proof of said "garbage" would be nice, but I won't hold my breath. 

> Well it's simple, you apply the contrapositive to material implication, 
> but don't know whether you're negating thusly what _was_ a true, 
> or, ..., _wasn't_, a false, all vacuous. 
> 
[snip]

You are making no sense.

	1.	A => B
		Premise

		2.	~B
			Premise

			3.	A
				Premise

			4.	B
				Detach, 1, 3

			5.	~B & B
				Join, 2, 4

		6.	~A
			Conclusion, 3

	7.	~B => ~A
		Conclusion, 2

8.	A => B => [~B => ~A]
	Conclusion, 1

This result doesn't depend of the truth value of either A or B. What combination of truth values do you imagine would negate this result? Alternatively, which is the first invalid statement here and why.

Dan

Download my DC Proof 2.0 freeware at http://www.dcproof.com
Visit my Math Blog at http://www.dcproof.wordpress.com

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Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-30 15:05 -0700
  Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-30 15:14 -0700
    Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-30 15:57 -0700
    Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-30 18:45 -0700
      Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 01:42 -0700
        Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 01:55 -0700
          Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 02:09 -0700
            Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 08:21 -0700
              Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 08:28 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 08:39 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 11:50 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 11:58 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 13:10 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 21:12 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 21:35 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 11:43 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 12:40 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 12:54 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-01 14:24 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 14:55 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 15:18 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-03 08:31 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-03 09:10 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-02 08:19 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-02 11:20 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-03 08:27 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-03 08:31 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-03 13:53 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-03 13:57 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-03 14:04 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-03 14:13 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-04 07:47 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-04 08:26 -0700
                Re: Why is model theory needed? Mild Shock <janburse@fastmail.fm> - 2023-06-04 17:53 +0200
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-04 15:31 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-04 17:21 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-04 17:30 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-04 17:39 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-04 17:49 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-05 08:20 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-05 10:56 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-05 13:16 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-05 13:17 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-05 15:10 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-05 14:07 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-05 15:09 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-05 17:51 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-05 22:54 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-06 18:44 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-06 21:02 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-07 11:42 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-07 13:48 -0700
                Re: Why is model theory needed? Mild Shock <janburse@fastmail.fm> - 2023-06-07 23:43 +0200
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-08 12:14 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-08 12:19 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 10:54 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 10:54 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 11:35 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-09 11:53 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 11:58 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:27 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-09 11:59 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:27 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-06 18:43 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 05:18 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 05:20 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 10:53 -0700
                Re: Why is model theory needed? Mild Shock <janburse@fastmail.fm> - 2023-06-09 21:28 +0200
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:27 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:28 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 15:45 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:51 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-09 15:51 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-09 15:57 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 16:03 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 16:09 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-09 16:19 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-09 16:20 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 16:21 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 16:28 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-09 16:28 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-10 08:25 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-10 09:08 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-10 09:13 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-10 12:52 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-10 13:21 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-11 08:25 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-11 08:44 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-11 09:06 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-11 10:55 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-11 11:54 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-11 13:12 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-11 13:59 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-11 15:26 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-11 15:31 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-11 15:34 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-12 08:31 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-12 08:39 -0700
                Re: Why is model theory needed? Jeffrey Rubard <theleasthappyfella@gmail.com> - 2023-06-12 08:56 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-12 09:00 -0700
                Re: Why is model theory needed? Jeffrey Rubard <theleasthappyfella@gmail.com> - 2023-06-12 09:07 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-12 09:22 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-12 09:37 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-12 09:50 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-12 10:13 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-12 08:31 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-12 08:30 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-06-10 12:51 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-10 15:13 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-10 15:19 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-11 08:25 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-10 08:24 -0700
              Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 13:05 -0700
        Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 08:15 -0700
          Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 11:41 -0700
            Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 11:48 -0700
            Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 12:52 -0700
              Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 13:06 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 13:28 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-05-31 18:53 -0700
              Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:18 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 13:53 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 13:58 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 14:06 -0700
                Re: Why is model theory needed? Jeffrey Rubard <jeffreydanielrubard@gmail.com> - 2023-05-31 14:08 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 15:57 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-05-31 16:46 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-05-31 17:31 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 02:48 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 03:02 -0700
                Re: Why is model theory needed? Ross Finlayson <ross.a.finlayson@gmail.com> - 2023-06-01 08:19 -0700
                Re: Why is model theory needed? Jeffrey Rubard <rehashedrubard@gmail.com> - 2023-06-01 08:42 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 07:07 -0700
                Re: Why is model theory needed? Dan Christensen <Dan_Christensen@sympatico.ca> - 2023-06-01 11:03 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 11:08 -0700
                Re: Why is model theory needed? Mild Shock <bursejan@gmail.com> - 2023-06-01 11:14 -0700

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