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| Started by | RichD <r_delaney2001@yahoo.com> |
|---|---|
| First post | 2011-12-31 18:03 -0800 |
| Last post | 2012-01-06 06:42 +0000 |
| Articles | 4 on this page of 44 — 20 participants |
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the hourglass problem RichD <r_delaney2001@yahoo.com> - 2011-12-31 18:03 -0800
Re: the hourglass problem William Elliot <marsh@rdrop.com> - 2011-12-31 19:21 -0800
Re: the hourglass problem Dave Dodson <dave_and_darla@Juno.com> - 2011-12-31 19:41 -0800
Re: the hourglass problem William Elliot <marsh@rdrop.com> - 2012-01-01 19:48 -0800
Re: the hourglass problem Patricia Shanahan <pats@acm.org> - 2012-01-01 20:44 -0800
Re: the hourglass problem William Elliot <marsh@rdrop.com> - 2012-01-01 23:08 -0800
Re: the hourglass problem Patricia Shanahan <pats@acm.org> - 2012-01-02 07:55 -0800
Re: the hourglass problem Dr Nick <3-nospam@temporary-address.org.uk> - 2012-01-02 16:17 +0000
Re: the hourglass problem Robert Wessel <robertwessel2@yahoo.com> - 2012-01-03 03:37 -0600
Re: the hourglass problem Remysun <remysun2000@yahoo.com> - 2012-01-02 17:10 -0800
Re: the hourglass problem "BartC" <bc@freeuk.com> - 2012-01-03 01:12 +0000
Re: the hourglass problem root <NoEMail@home.org> - 2012-01-01 05:51 +0000
Re: the hourglass problem William Elliot <marsh@rdrop.com> - 2012-01-01 20:04 -0800
Re: the hourglass problem Duncan Booth <duncan.booth@invalid.invalid> - 2012-01-02 11:42 +0000
Re: the hourglass problem RichD <r_delaney2001@yahoo.com> - 2012-01-03 15:05 -0800
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-03 15:19 -0800
Re: the hourglass problem PT <ptanenbaum@consultant.com> - 2012-01-04 12:28 -0800
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-04 13:44 -0800
Re: the hourglass problem Dave Dodson <dave_and_darla@Juno.com> - 2012-01-04 22:55 -0800
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-04 23:55 -0800
Re: the hourglass problem "Harry Vaderchi" <admin@127.0.0.1> - 2012-01-05 10:06 +0000
Re: the hourglass problem "BartC" <bc@freeuk.com> - 2012-01-05 13:44 +0000
Re: the hourglass problem Patricia Shanahan <pats@acm.org> - 2012-01-05 08:13 -0800
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-05 11:55 -0800
Re: the hourglass problem JohnF <john@please.see.sig.for.email.com> - 2012-01-06 04:40 +0000
Re: the hourglass problem Dave <dave_and_darla@Juno.com> - 2012-01-05 15:37 -0800
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-05 16:02 -0800
Re: the hourglass problem Duncan Booth <duncan.booth@invalid.invalid> - 2012-01-02 11:50 +0000
Re: the hourglass problem Frederick Williams <freddywilliams@btinternet.com> - 2012-01-02 17:18 +0000
Re: the hourglass problem msb@vex.net (Mark Brader) - 2012-01-02 17:40 -0600
Re: the hourglass problem RichD <r_delaney2001@yahoo.com> - 2012-01-02 17:37 -0800
Re: the hourglass problem msb@vex.net (Mark Brader) - 2012-01-02 23:45 -0600
Re: the hourglass problem "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2012-01-03 10:06 +0100
Re: the hourglass problem Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2012-01-03 12:51 +0100
Re: the hourglass problem Nicolas Neuss <lastname@scipolis.de> - 2012-01-03 18:07 +0100
Re: the hourglass problem Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2012-01-03 21:58 +0100
Re: the hourglass problem Frederick Williams <freddywilliams@btinternet.com> - 2012-01-03 13:22 +0000
Re: the hourglass problem "BartC" <bc@freeuk.com> - 2012-01-03 12:59 +0000
Re: the hourglass problem Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2012-01-03 12:47 +0100
Re: the hourglass problem Frederick Williams <freddywilliams@btinternet.com> - 2012-01-05 14:09 +0000
Re: the hourglass problem Patricia Shanahan <pats@acm.org> - 2012-01-05 08:17 -0800
Re: the hourglass problem Frederick Williams <freddywilliams@btinternet.com> - 2012-01-05 16:27 +0000
Re: the hourglass problem Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-01-05 11:57 -0800
Re: the hourglass problem JohnF <john@please.see.sig.for.email.com> - 2012-01-06 06:42 +0000
Page 3 of 3 — ← Prev page 1 2 [3]
| From | Patricia Shanahan <pats@acm.org> |
|---|---|
| Date | 2012-01-05 08:17 -0800 |
| Message-ID | <EMGdnex0TpGqUJjSnZ2dnUVZ_sqdnZ2d@earthlink.com> |
| In reply to | #1220 |
Frederick Williams wrote: > RichD wrote: >> You're given a 7 minute, and a 4 minute, sand >> hourglass. > > What may one do with these hourglasses? Turn them over, certainly, but > may one place them on their side so that they stop "ticking"? > Could someone with an actual hourglass check whether that works? I would have thought that most of the time the level of sand in one side would still be above the hole. If so, does the sand really stop flowing? Patricia
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| From | Frederick Williams <freddywilliams@btinternet.com> |
|---|---|
| Date | 2012-01-05 16:27 +0000 |
| Message-ID | <4F05CF82.CF7560B1@btinternet.com> |
| In reply to | #1222 |
Patricia Shanahan wrote: > > Frederick Williams wrote: > > RichD wrote: > >> You're given a 7 minute, and a 4 minute, sand > >> hourglass. > > > > What may one do with these hourglasses? Turn them over, certainly, but > > may one place them on their side so that they stop "ticking"? > > > > Could someone with an actual hourglass check whether that works? I would > have thought that most of the time the level of sand in one side would > still be above the hole. If so, does the sand really stop flowing? I have a three minute egg timer the sand in which stops flowing when it is laid on its side even when most of the sand is in one bulb. And even if it didn't, one can place it a little off the horizontal so that the greater part of the sand falls back from the hole a little, but the rest of the sand (the lesser amount) does not get near the hole. That this works may be because of the shape of the bulbs and YBSMV. I write "sand", but it is some finely divided green stuff. -- When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him. Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting
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| From | Daniel Pitts <newsgroup.nospam@virtualinfinity.net> |
|---|---|
| Date | 2012-01-05 11:57 -0800 |
| Message-ID | <mgnNq.66081$_H.29761@newsfe16.iad> |
| In reply to | #1222 |
On 1/5/12 8:17 AM, Patricia Shanahan wrote: > Frederick Williams wrote: >> RichD wrote: >>> You're given a 7 minute, and a 4 minute, sand >>> hourglass. >> >> What may one do with these hourglasses? Turn them over, certainly, but >> may one place them on their side so that they stop "ticking"? >> > > Could someone with an actual hourglass check whether that works? I would > have thought that most of the time the level of sand in one side would > still be above the hole. If so, does the sand really stop flowing? I would suspect it depends on the shape of the bulbs, but I have seen that technique used in real life situations. For instance, "pausing" a game while someone uses the restroom or answers the door.
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| From | JohnF <john@please.see.sig.for.email.com> |
|---|---|
| Date | 2012-01-06 06:42 +0000 |
| Message-ID | <je654e$plu$1@reader1.panix.com> |
| In reply to | #1222 |
In sci.logic Patricia Shanahan <pats@acm.org> wrote: > Frederick Williams wrote: >> RichD wrote: >>> You're given a 7 minute, and a 4 minute, >>> sand hourglass. >> >> What may one do with these hourglasses? >> Turn them over, certainly, but may one place >> them on their side so that they stop "ticking"? > > Could someone with an actual hourglass check whether that works? What's the diff? As per my preceding post, the more interesting abstract problem is: given a particular "instruction set" (that's apparently not Turing complete), what's the "computable" subset of N? Here, the available hourglasses are maybe like registers or memory locations (I'm not sure what a good computer analogy would be here), and the turn-over operations are like the instruction set. The contents of these "memory locations" aren't really bits, or even bit-like, and so the instructions don't do the usual things, and therefore presumably don't have the usual semantics (though it seems pretty easy to associate them with subsets of N). What seems interesting to me is to try to firm up this kind of analogy, and see if anything worth talking about emerges. -- John Forkosh ( mailto: j@f.com where j=john and f=forkosh )
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