Skip to main content
13 events
when toggle format what by license comment
May 28, 2022 at 1:03 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Apr 29, 2022 at 6:12 comment added Thomas Benjamin @FrançoisG.Dorais: is it possible that Siegel's Lemma is $\Delta_1$ rather than $\Pi_1$?
Apr 27, 2022 at 22:14 answer added Thomas Benjamin timeline score: 1
Apr 12, 2022 at 20:58 history edited Thomas Benjamin CC BY-SA 4.0
added seigel's lemma at suggestion of comment
Apr 12, 2022 at 20:44 history edited Thomas Benjamin CC BY-SA 4.0
added seigel's lemma at suggestion of comment
Apr 10, 2022 at 10:18 comment added Thomas Benjamin @FrançoisG.Dorais: since you mentioned that Siegel's Lemma was probably provable in $EFA$, what factors would possibly keep it from being provable in $EFA$?
Apr 10, 2022 at 8:58 comment added Thomas Benjamin Thanks. This is very helpful.
Apr 10, 2022 at 7:51 comment added François G. Dorais To see that it is provable in EFA, I would just go through the proof carefully. It only uses the finite pigeonhole principle, so this has nothing to do with second-order arithmetic, this is about first-order arithmetic. So the context you set out is incorrect. To draw the right attention, you need to recast in terms of subsystems of first-order arithmetic.
Apr 10, 2022 at 7:25 comment added Thomas Benjamin @FrançoisG.Dorais: it is provability in $EFA$ that interests me (and yes, that's the theorem I am referring to). I have been led to believe that the two systems of second-order arithmetic I have mentioned in my question have the same consistency strength as $EFA$ and are conservative over it for $\Pi_2$ sentences (via the Wikipedia entry for $EFA$). How would you go about proving that Seigel's Lemma is provable in $EFA$ (or could give me a reference where that has been already done)?
Apr 10, 2022 at 5:03 comment added François G. Dorais That paper is very interesting but it has nothing to do with Siegel's Lemma. It would be useful to include a statement of Siegel's Lemma with the question. Assuming this is the lemma I think about, this is about bounds for nontrivial solutions of systems of linear homogeneous equations with rational coefficients. If I'm correct, this looks like a $\Pi_1$ statement at best. Second-order arithmetic is the wrong target. It's certainly provable in PRA and probably provable in EFA.
Apr 10, 2022 at 1:03 history edited Thomas Benjamin CC BY-SA 4.0
Added period
Apr 10, 2022 at 0:03 history edited Gerry Myerson CC BY-SA 4.0
typos
Apr 9, 2022 at 20:32 history asked Thomas Benjamin CC BY-SA 4.0