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May
22
comment how to prove Euler Characteristic of cw complex $\chi(X)=\chi (A)+\chi (B)-\chi (A \cap B)$.
Well, can you indeed? If unsure, consider some examples first...
May
22
comment how to prove Euler Characteristic of cw complex $\chi(X)=\chi (A)+\chi (B)-\chi (A \cap B)$.
Great. Do you know any theorem linking together H(X), H(A), H(B) and H(intersection)?..
May
22
comment how to prove Euler Characteristic of cw complex $\chi(X)=\chi (A)+\chi (B)-\chi (A \cap B)$.
What is your definition of $\chi$?
May
22
reviewed Close Proving that if $f$ is an increasing function on $I \subset \mathbb{R}$, then $\lim_{y \to x^{-}} f(y)$ and $\lim_{y \to x^{+}} f(y)$ exists.
May
22
reviewed Close Create a graph with these conditions…
May
22
reviewed Close Does right continuity imply only countably many discontinuities?
May
22
reviewed Close Coordinate-free proof of determinant of transpose
May
21
revised Direct proof that for a prime $p$ if $p\equiv 1 \bmod 4$ then $l(\sqrt{p})$ is odd.
edited tags
May
21
comment Open covers by simply connected sets and fundamental group
@Daniel, OP — oh, I'm sorry, I misread the question
May
21
revised Open covers by simply connected sets and fundamental group
more descriptive title
May
21
awarded  Nice Answer
May
20
reviewed Close Finding an area of a propeller using double integration? Attempted, please help! :(
May
20
revised Fibonacci combinatorial identity
edited tags
May
20
answered Fibonacci combinatorial identity
May
20
answered Binomial Sum Related to Fibonacci: $\sum\binom{n-i}j\binom{n-j}i=F_{2n+1}$
May
20
comment Reference request for Rothenberg Steenrod Spectral Sequence
@draks... I guess, neil-strickland.staff.shef.ac.uk/courses/bestiary/ss.pdf
May
20
reviewed Close How many different committees of 5 can be formed from 8 men and 7 women such that there are at least 2 women in the committee
May
20
reviewed Close Find the maximum possible area
May
20
revised Finding integral solutions to the equation $x^4-ax^3-bx^2-cx-d=0$
edited title
May
20
reviewed Close Calculus-Tangent Line Slope