13,170 reputation
41059
bio website
location
age
visits member for 1 year, 10 months
seen 7 hours ago

7h
accepted “Elements” of algebraic structures
1d
revised Why does this graph only the positive side
added 330 characters in body
1d
revised Find the total area of the path?
edited tags
1d
accepted A question about second-order logic and inaccessible cardinals.
1d
comment A question about second-order logic and inaccessible cardinals.
Thanks. Any ideas whether or not the property of interest implies that $M=V_\kappa$ for some cardinal $\kappa$?
1d
comment Polar form of a complex number
I was thinking more along the lines of: its just a pain to try explaining why $e^{i\theta} = \cos \theta + i \sin \theta$ in a basic, introductory course in which the students have no analysis or knowledge of infinite summations under their belt. Better to just write $\mathrm{cis}\,\theta$ and be done with it.
1d
comment Polar form of a complex number
(Slightly unrelated) I like $\mathrm{cis},$ pedagogically it just makes a lot of sense.
1d
asked A question about second-order logic and inaccessible cardinals.
Jul
25
accepted In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
Jul
25
comment In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
@Bryan, yes. $\,\!$
Jul
25
comment In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
@Gina, I think that's a proof.
Jul
25
comment In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
@Gina, in general group theory, all we know is that $XY \subseteq X \vee Y$. In particular, there is no guarantee that $XY$ is a group.
Jul
25
revised In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
deleted 1 character in body
Jul
25
asked In group theory, is it true that $f(X \vee Y) = f(X) \vee f(Y)$?
Jul
25
revised Has anyone succeeded in formalizing Leibniz notation in such a way that the chain rule and inversion rule “work”?
added 9 characters in body
Jul
25
revised Are there any good documentary films about the continuum hypothesis?
deleted 437 characters in body
Jul
25
asked Has anyone succeeded in formalizing Leibniz notation in such a way that the chain rule and inversion rule “work”?
Jul
25
answered A consistent set of formulas
Jul
24
comment What are some 'conceptualizations' that work in mathematics but are not strictly true?
I think the second dot point is correct, though.
Jul
24
comment What are some 'conceptualizations' that work in mathematics but are not strictly true?
@vonPetrushev, but photons do have a relativistic mass. That is surely the simplest explanation as to why they're able to impart momentum on solar sails.