155,955 reputation
15209418
bio website boolesrings.org/asafk
location Israel
age 29
visits member for 3 years, 11 months
seen 2 hours ago

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

Set theorist to-be.


3h
comment Maximal model for $\Bbb R$?
But there are no "corresponding values". How can there be if one model has more integers than the second model has sets? (For example...) I think that the issue is that you don't understand why having different sets of integers means that the real numbers are different. Think about it. Long and hard.
4h
comment Maximal model for $\Bbb R$?
Do you see why this is not possible when $M$ and $M'$ have different sets as their integers?
4h
comment Maximal model for $\Bbb R$?
But how would you "add it to the model"? And when you do, why would it be a real number in the new model?
7h
comment Show that T2-space is preserved by continuous map.
Where is the one-to-one condition comes into play?
7h
comment Show that T2-space is preserved by continuous map.
This is not preservation. Preservation would be the other implication.
7h
revised How to derive the process noise co-variance matrix Q in this Kalman Filter example?
edited tags
8h
comment Show that a map f : (X,$\tau$) $\rightarrow$ (Y,$\tau_1$) is continuous if and only if $f^{-1}(U)\in\tau$ , for every $U\in$B1
It's important to remember your assumptions!
8h
comment Show that a map f : (X,$\tau$) $\rightarrow$ (Y,$\tau_1$) is continuous if and only if $f^{-1}(U)\in\tau$ , for every $U\in$B1
Please state, here, explicitly what is the assumption that you started from. And what exactly is $U$.
11h
reviewed Leave Closed How prove this $\sum_{k+j=n,0\le k,j\le n}\binom{2k}{k}\binom{2j}{j}=4^n$
12h
comment Examples of “Non-Logical Theorems” Proven by Logic
What's "mathematical logic" in this case?
13h
revised Question about proof on closed sets using convergence
edited tags
14h
comment Prove or disprove the syntactic consequence.
Well, I expected this to be a question about the completeness theorem.
14h
comment Prove or disprove the syntactic consequence.
Why is the title saying "Models", then? Models are semantics, not syntactic. I expected a whole other question inside.
14h
comment Maximal model for $\Bbb R$?
It's a troublesome question. If you know enough set theory, you can probably answer it yourself; if you don't then many of the delicate points are often lost on you and any proper answer will be lost on you. I hope that I managed to make some sense in my answer, but I fear that I have not.
14h
answered Maximal model for $\Bbb R$?
19h
comment How to convince a layman that there are as many rationals as integers
@mistermarko: If that's true?
19h
comment How to convince a layman that there are as many rationals as integers
@mistermarko: The axiom of choice has nothing to do with the countability of the rationals.
1d
reviewed No Action Needed Connection defined by its geodesics
1d
comment Show that a map f : (X,$\tau$) $\rightarrow$ (Y,$\tau_1$) is continuous if and only if $f^{-1}(U)\in\tau$ , for every $U\in$B1
Have you used the assumption yet?
1d
comment Closure Question in Enderton's 'Elements of Set Theory'
@William: I suppose the one from the previous question.