meta user
network profile
| bio | website | |
|---|---|---|
| location | ||
| age | ||
| visits | member for | 2 years, 1 month |
| seen | Jan 16 at 14:48 | |
| stats | profile views | 56 |
|
Apr 14 |
awarded | Yearling |
|
Apr 10 |
awarded | Good Answer |
|
Jan 11 |
comment |
Clarification of a remark of J. Steel on the independence of Goldbach from ZFC @alancalvitti No because the Euclidean axioms are not $\Pi^0_1$-sound. |
|
Jan 11 |
accepted | Clarification of a remark of J. Steel on the independence of Goldbach from ZFC |
|
Jan 10 |
comment |
Clarification of a remark of J. Steel on the independence of Goldbach from ZFC By the way, I am not the one who downvoted |
|
Jan 10 |
comment |
Clarification of a remark of J. Steel on the independence of Goldbach from ZFC Thanks a lot for the super quick response, but I'm afraid I don't understand. What is M[G]? What are we assuming about M? I'm sorry but I don't see how Steele's remark follows from this at all...Is the idea this: Let's start with any model M of ZFC and then force a model 'M[G]' in which $\phi$ is true (or false), then $\phi$ is true or false in the model we started with? But how does that ensure it is provable in PA? Why couldn't it turn out to be undecidable? Could I convince you to expand on your answer? |
|
Jan 10 |
asked | Clarification of a remark of J. Steel on the independence of Goldbach from ZFC |
|
Aug 13 |
comment |
Where else has Proposition B1.3.17 in the Elephant been proved? @QiaochuYuan I know cross-posting is discouraged, but would it be bad form if I re-posted this on mathoverflow? |
|
Aug 13 |
comment |
Where else has Proposition B1.3.17 in the Elephant been proved? @ZhenLin Yes I do have Streicher's notes which are generally very helpful. He proves this result for the specific property of local smallness (Lemma 13.3) but not the much more general result that Johnstone proves. Of course reading Streicher more carefully, he seems to imply (top of pg. 47, just before the proof of 13.3) that Benabou also only proved such results for specific properties. So it seems Johnstone was the first to present this result in this general form - and therefore that this is the only proof that we have... |
|
Aug 12 |
comment |
What is the formula for this exponentially growing “stairs”? Do you need all the points (i.e. the where the vertical meets the horizontal) of each step to lie on a straight line? |
|
Aug 11 |
comment |
Where else has Proposition B1.3.17 in the Elephant been proved? @Qiaochu Haha, you are right - I meant the former, i.e. so condensed as to make it difficult to understand. |
|
Aug 11 |
asked | Where else has Proposition B1.3.17 in the Elephant been proved? |
|
Aug 7 |
comment |
Why is the landing footprint an ellipse? Yes, thanks, I appreciate your answer but that's exactly what I wrote in the question - I was asking whether there's anything more than that |
|
Aug 6 |
asked | Why is the landing footprint an ellipse? |
|
May 4 |
comment |
How to get a geometric morphism out of a section? (And general pedagogy on classifying toposes) Thanks for this answer. I don't understand what version of the SAFT you are using there (which I associate with the existence of a left adjoint)? I'm assuming what you have in mind is the theorem that says that a functor between Grothendieck toposes has a right adjoint iff it preserves colimits. However we cannot know that the toposes in question here are Grothendieck. Maybe I'm missing something.... |
|
May 2 |
awarded | Nice Answer |
|
May 2 |
comment |
In the history of mathematics, has there ever been a mistake? @Zarrax I suspected he must've had some serious formal training in math, but never knew that - edited accordingly |
|
May 2 |
revised |
In the history of mathematics, has there ever been a mistake? added 19 characters in body |
|
May 2 |
comment |
In the history of mathematics, has there ever been a mistake? Oh I didn't notice it had been given there - apologies, that one's a better answer.... |
|
May 2 |
answered | In the history of mathematics, has there ever been a mistake? |
