2,253 reputation
1224
bio website textproof.com/stewart
location Berlin, Germany
age 44
visits member for 4 years, 1 month
seen Jun 27 at 7:01

Freelance copy-editor.


You can read my irregular waffles at advogato.org/person/chalst/.


I have a Math Overflow account.


Jul
20
awarded  Yearling
Jul
2
awarded  Curious
Jun
24
comment Why an inconsistent formal system can prove everything?
@Blaisorblade - if you mean that abstract syntax can solve the issue with substitution, then I guess that most mathematicians have little idea of the work done in this field.
May
1
awarded  Pundit
Apr
4
reviewed Approve suggested edit on Matlab program of a finite sum that returns the result in a matrix
Apr
4
reviewed Approve suggested edit on Powers of permutation matrices.
Apr
3
awarded  Custodian
Apr
3
reviewed Reject suggested edit on From centroid and two vertexes to find the missing vertex of a triangle.
Apr
2
comment What precisely is a vacuous truth?
@MJD: I don't think much of the WP article. It doesn't link its definitions to the sources it lists, and it does not relate to well-known related topics. The claim 'A statement S is "vacuously true" if it resembles the statement $P \Rightarrow Q$, where P is known to be false' is unattributed, imprecise (resembles?, no outermost quantifier?, does "known" mean this is an epistemic claim?) and I would say is false (rather, vacuous truths "resemble" a special case of this form), and the well-known example is generally described as a paradox of material implication.
Apr
2
comment What is the antiderivative of $e^{-x^2}$
What you call the elementary functions, Hardy called the logarithmico-exponential functions: pp. 54-90 of plms.oxfordjournals.org/content/s2-10/1
Dec
13
revised Basic Tautology Question
right != left
Dec
13
answered Basic Tautology Question
Nov
7
answered Deduction Theorem Subtlety and Predicate Proof
Nov
4
awarded  Popular Question
Oct
14
comment Where did mathematicians learn how to do truth tables?
To support what @amWhy says, before his contact with Frege, Wittgenstein's studies were (according to Ian Lemke) in mechanical engineering, physics, philosophy of science and aeronautical engineering. See rsnr.royalsocietypublishing.org/content/61/1/39.full - tyh
Jul
20
awarded  Yearling
Jun
10
answered What is a Herbrand disjunction?
May
15
comment Cardinality of the set of prime numbers
+1 for avoiding Axiom-of-choice -strength principles in your answer.
May
7
awarded  Caucus
May
3
comment Why an inconsistent formal system can prove everything?
@Joshua: All the theorems and valid inference rules involving $\perp$ are still theorems/ valid rules if you substitute that symbol by any other proposition: there is no difference between that symbol and a schematic variable.