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James's user avatar
James's user avatar
James
  • Member for 10 years, 10 months
  • Last seen more than 1 year ago
23 votes

Are all symmetric matrices ​invertible?

17 votes

$10=c+d$ and $c$ is one more than $d$.

11 votes

How can an open set be equal to a union of half-open sets?

11 votes

Calculating discount not working

10 votes
Accepted

Square root inside a square root

8 votes
Accepted

Show that the discrete topology on $X$ is induced by the discrete metric

6 votes
Accepted

Can someone please explain the axiom of induction in lay term?

5 votes
Accepted

A room and a spider

5 votes
Accepted

Idiomatic mathematical english statement for ∃x[P(x) ∧ ∀y(P(y) → y ≤ x)]

5 votes

Union of connected subsets is connected if intersection is nonempty

5 votes
Accepted

Difference between Oriented Graph and Directed Acyclic Graphs (DAG)

4 votes

Where does $\in$ come from and where is it defined?

4 votes

Find two rationals, one greater and one smaller than a given irrational number.

4 votes
Accepted

Bounded linear operator in a normed space, $Tf=f(0)$ on $C[0,1]$

4 votes

is f(x,y) continuous at (0,0)?

4 votes
Accepted

Runtime Analysis, Coefficients in logarithms? Ignorable?

4 votes
Accepted

How to determine whether an isomorphism $\varphi: {U_{12}} \to U_5$ exists?

4 votes

Why can't AND and NOT be represented with only IMPLICATION?

4 votes

How to find the domain interval of an inverse function

4 votes
Accepted

Elementary problem in geometry

4 votes
Accepted

How to prove abelian group

4 votes
Accepted

How Do I Figure Out Which Door to Choose From?

4 votes
Accepted

Find a subbasis $\mathcal S$ for $\mathcal T$ such that $\mathcal S$ does not contain any singleton sets.

4 votes
Accepted

Propositional Logic: (p ∧ q) → r ⊢ (p → r) ∨ (q → r)

3 votes
Accepted

product $\sigma$-algebra equals the set of all countable unions of disjoint measurable rectangles?

3 votes

Writing the integral of f(x) without any variables to find C.

3 votes

Is this symbolic statement impossible?

3 votes

Real and Non-real Numbers; Value of Zero?

3 votes

Set of formulas has no model

3 votes
Accepted

Just started group theory. Need help with some basic concepts.

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