Timeline for Nelson natural number objects in a topos (say)
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Jan 28, 2013 at 23:03 | comment | added | David Roberts♦ | Hmm, ok. I'll have a look at it. Thanks! | |
| Jan 27, 2013 at 9:06 | comment | added | Wouter Stekelenburg | When linear logic was introduced by Girard, $!$ was a comonad. In order to get control over complexity, however, you have to let go of $!\alpha\to !!\alpha$, I think. | |
| Jan 27, 2013 at 2:08 | comment | added | David Roberts♦ | An NNO corresponds to Peano's original formulation, which is second-order, but is not the same thing as second-order arithmetic $Z_2$. (I don't think I knew this when I asked this question.) Perhaps we could have some sort of comonad which encodes the modalities summable and multiplicable, not necessarily $!$. | |
| Jan 26, 2013 at 12:30 | history | edited | Wouter Stekelenburg | CC BY-SA 3.0 |
added 1096 characters in body
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| Jan 25, 2013 at 18:06 | comment | added | François G. Dorais | This is the wrong point of view. Every topos with a nno has a unique nno, but not all toposes have the same nno. The nnos that occur in this way are known - mathoverflow.net/questions/93631/nno-first-order-pa David is asking whethere there is a class of categories and "nnnos" that correspond to Nelson's theory. | |
| Jan 25, 2013 at 16:35 | history | answered | Wouter Stekelenburg | CC BY-SA 3.0 |