155,445 reputation
15207417
bio website boolesrings.org/asafk
location Israel
age 29
visits member for 3 years, 11 months
seen 2 mins ago

Ph.D. student in the Hebrew University of Jerusalem.

Set theorist to-be.


41m
awarded  Nice Answer
4h
comment How to find an everywhere discontinuous real function with $F((a+b)/2)<(F(a)+F(b))/2$?
Again, the axiom of choice tag is not for "Well, this probably needs the axiom of choice". It's for asking specific questions about the axiom of choice. You already asked that part, you were told that the axiom of choice is needed to some degree in constructing a solution. Now you just seem to ask "Well, how can I construct this sort of solution?" and that's not quite what fits to the axiom of choice tag.
4h
revised Can we deduce that $X$ is $\sigma-$compact?
edited tags
4h
comment How to find an everywhere discontinuous real function with $F((a+b)/2)<(F(a)+F(b))/2$?
Yeah, that is probably an application of the axiom of choice. As are 60% of modern functional analysis, parts of ring theory, group theory, and in fact even freshman year calculus.
4h
revised A question on $\sigma-$compact spaces
edited tags
4h
comment How to find an everywhere discontinuous real function with $F((a+b)/2)<(F(a)+F(b))/2$?
This isn't really a question about the axiom of choice. This is a question about finding a function which satisfies this inequality. The [axiom-of-choice] tag is unnecessary here.
5h
revised How to find an everywhere discontinuous real function with $F((a+b)/2)<(F(a)+F(b))/2$?
edited tags
5h
revised How to find an everywhere discontinuous real function with $F((a+b)/2)<(F(a)+F(b))/2$?
edited tags
5h
comment A Question Regarding Forcing in Gödel's Constructible Universe in Infinitary Logics
@Thomas: I have no idea what you're trying to ask.
15h
awarded  Good Question
15h
comment Why is adding Cohen reals so “uninteresting”?
We have a moderator which might be able to give a nice answer, but maybe I've just put him on the spot and he won't like it... :-P
15h
reviewed No Action Needed Composing a smooth even function and square root
16h
revised $x^y < y^x$ for $y\ll x$?
added 1 character in body; edited title
16h
comment Example of first order logic without equality.
Well, I don't know if it's my non-native ears, but traditional makes it sound as if that's how it's "usually goes down, for generations" rather than "how it went down half a century ago".
16h
comment Example of first order logic without equality.
Let me point out about set theory, that in all the modern textbooks which give a full treatment to axiomatic set theory, equality is indeed part of the language. (The list includes Jech, Kunen, Kanamori, and Halbeisen - and probably a few more.)
17h
comment How to show if A is denumerable and $x\in A$ then $A-\{x\}$ is denumerable
This cannot not be a duplicate.
17h
comment Does there exist two distinct set which are not an element of a given infinite set?
I literally don't understand your comment.
19h
comment What are $\in$-well orderable classes?
You're wrong. $0\in1$.
19h
comment Does there exist two distinct set which are not an element of a given infinite set?
Also, in modern set theory everything is a set. Including integers. There are no types, these are superimposed on sets as needed. If $X$ is a non-empty set, then all its elements are sets as well.
19h
comment Does there exist two distinct set which are not an element of a given infinite set?
Sets have mathematical objects. Presidential candidates are not mathematical objects. Therefore the "set of presidential candidates from the last election cycle" does not exist at all.