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sxd
  • Member for 13 years
  • Last seen more than a month ago
23 votes
Accepted

Prove that the center of a group is a normal subgroup

17 votes

Bag of tricks in Advanced Calculus/ Real Analysis/Complex Analysis

14 votes
Accepted

$\dfrac{\mathrm d}{\mathrm dx}x^x=$?

12 votes

What is the result of sum $\sum\limits_{i=0}^n 2^i$

12 votes

Is my proof that $(A^n)^{-1} = (A^{-1})^n$ correct?

12 votes
Accepted

Is the set of all positive real numbers dense in $\mathbb{R}$

11 votes
Accepted

Graph isomorphic

8 votes
Accepted

Do there exist exponential-time problems, even if $P=NP$

7 votes

Triangle Inequality with complex numbers: Prove that $ |z_{1} - z_{2}| \le |z_{1}| + |z_{2}| $.

6 votes

How to Prove a Programming Language is Turing Complete?

6 votes
Accepted

What is the CFG of the language that generates all strings over alphabet $\{a, b, c\}$?

5 votes

Differentiating the polynomial $x^3 - 4x +6$

5 votes

Find $n\in \mathbb N$ so that $(\mathbb Z_n, +, \cdot)$ has exactly 4 invertible elements and 5 zero-divisors

4 votes
Accepted

How to guess whether a language is regular or not

4 votes
Accepted

The print problem: How to show it is not decidable?

4 votes

How might I refresh high school level mathematics and extend it much further?

4 votes

Bernoulli's representation of Euler's number, i.e $e=\lim \limits_{x\to \infty} \left(1+\frac{1}{x}\right)^x $

3 votes
Accepted

Mathematics necessary for a Master's degree in CS

3 votes

How to add compound fractions?

3 votes

Map of Cartesian Product

3 votes

Mathematician (non-logician) seeks reference for Gödel's incompleteness theorems

3 votes
Accepted

Difference of Logarithms to form a quotient?

3 votes
Accepted

Sipser's proof of NP-completeness of SAT

3 votes

Is there any decidable problem that is NOT NP-HARD?

3 votes

Basic set questions

3 votes

The space $C_b(\mathbb{R})$ is complete

3 votes

What step am I missing in this?

3 votes

What is the significance of the order in an ordered basis/basis?

3 votes

The direct product of groups is abelian iff each group is abelian

3 votes

Questions about a commutative ring with exactly three ideals