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User12345
  • Member for 8 years, 2 months
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8 votes
Accepted

A deformation retract that is not a strong deformation retract

5 votes
Accepted

How do I prove that $-\sqrt{x-1}+\sqrt{x} \to 0$ as $x\to +\infty $?

5 votes

Showing planarity of graphs

4 votes

How do I show that the equivalence relation defining the rational numbers is transitive?

4 votes
Accepted

Prove that Proclus' axiom is equivalent to Playfair's axiom

3 votes
Accepted

Why is $\frac{d(x^n)}{d(x)}=nx^{n-1}$

3 votes
Accepted

$B\subset S$ is closed in $S$ iff it is equal to the intersection of $S$ with some closed subset of $X$

3 votes

1-manifold is orientable

3 votes
Accepted

Suppose $\mathcal{C}$ is a category, is it true that if a composition $f\circ g$ of two morphisms is an epimorphism, then $f$ is an epimorphism?

2 votes
Accepted

Show that $F_2^4$ is a union of three proper subspaces

2 votes

Is there anything to prove in this corollary?

2 votes
Accepted

Show that $(m-1)^{n-1}*n^{m-2}=\binom{n+m-1}{n}$

2 votes

Properties shared by similar and unitary similar matrices.

2 votes
Accepted

Prove $I = (m)$

2 votes

A set $S$ has $n$ elements. How many ways we can choose subsets $P$ and $Q$ of $S$, so that $P \cap Q$ is $\emptyset$?

2 votes
Accepted

For which values of $n$ is $f$ one-to-one/onto?

2 votes

Function defined on R and discontinuous at all points

2 votes
Accepted

Equivalence relations and commutative diagrams

2 votes
Accepted

How many solutions does $\left(a-x\right)\left(b-x\right)=\left(1-ax\right)\left(1-bx\right)$ have?

1 vote

If $(X, \mathcal{T})$ has a countable subbasis, then it has a countable basis

1 vote

If $\prod (X_i,T_i)$ is connected, then each $(X_i, T_i)$ is connected.

1 vote

Product of coverings is a covering of product space.

1 vote
Accepted

Does $A^{-1}$ exist?

1 vote
Accepted

Prove that the following argument is valid

1 vote

The difference between subgraph and component

1 vote

Show that $[-1,1] \times [-1,1]$ is a closed set.

1 vote

In the finite field $F$ of characteristic $p$, is $a^{p^n} = a$?

1 vote

Let $A = \{0\} \cup [1,2] \cup \{3\}$ and $ B = [0,1] \cup \{2\} \cup \{3\}$ proof there is no homeomorphism

1 vote

Proper use of indicator function

1 vote

Order $n$ elements of infinite groups of finite exponent $n>2$