Timeline for A question about sentences undecidable in Peano's Arithmetic
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Jul 25, 2015 at 1:51 | comment | added | David Roberts♦ | OK, thanks. I was worried you had access to some higher truth somehow, rather than working in ZFC. | |
| Jul 24, 2015 at 17:43 | vote | accept | Garabed Gulbenkian | ||
| Jul 24, 2015 at 14:50 | comment | added | Andreas Blass | @DavidRoberts The facts that Con(SOA) is true, that all axioms of SOA are true, that logical inference preserves truth, and that therefore Con(SOA) cannot be refuted in SOA are all provable in the usual foundational system for mathematics, ZFC. (They're also provable in far weaker systems,but I don't think that's needed to answer "How does one get this?") | |
| Jul 24, 2015 at 5:26 | comment | added | David Roberts♦ | "...and it's not refutable because it's true." really? How does one get this? | |
| Jul 23, 2015 at 18:44 | comment | added | Andreas Blass | Note that Gödel's paper on the incompleteness theorems is, as indicated in its title, about Principia Mathematica and related systems. Principia Mathematica is considerably stronger than SOA. | |
| Jul 23, 2015 at 18:43 | history | answered | Andreas Blass | CC BY-SA 3.0 |