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Hermis14
  • Member for 8 years, 1 month
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7 votes
0 answers
150 views

Differential geometry: non-uniqueness of the closest point on a curve

5 votes
1 answer
127 views

Topology: Boundary of a set

3 votes
1 answer
97 views

Uniqueness of the topology on $\mathbb{R}$

3 votes
1 answer
366 views

ODE: The Lyapunov stability of a set

3 votes
2 answers
723 views

Definition of the largest or smallest set that has some property

3 votes
1 answer
158 views

What does a set of functions from $A$ to $B$ belong to?

3 votes
1 answer
174 views

A proof of $|\mathbb{N}| = |\mathbb{N} \times \mathbb{N}|$

3 votes
1 answer
67 views

What does the expression 'a closed subset of a set' imply?

2 votes
1 answer
170 views

A sublevel set and its boundary of a differentiable function

2 votes
0 answers
37 views

Applying mathematical induction to a statement involving two integers

2 votes
0 answers
92 views

Does $|\mathcal{P}(X)| = |\mathcal{P}(Y)|$ imply $|X| = |Y|$? [duplicate]

2 votes
0 answers
92 views

Finding an injection from $\mathcal{P}(\mathbb{N})$ to $\mathbb{R}$ by using power series of base $2$.

2 votes
1 answer
237 views

The image from finite set is finite / Axiom of choice

2 votes
1 answer
81 views

There is no bijection between $I_n$ and $\mathbb{N}$.

2 votes
1 answer
45 views

Finite Cartesian product of naturals is countably infinite + notation.

2 votes
1 answer
152 views

Understanding axiom of choice from examples

2 votes
1 answer
74 views

Quantification and the existence of a function

2 votes
1 answer
77 views

In the Garling's proof of 'AC implies Zorn's lemma'

2 votes
1 answer
76 views

The advantage of defining open/closed sets using sequence.

2 votes
1 answer
175 views

Equivalent definitions of convex hull

2 votes
0 answers
54 views

Logic - Existential quantification and axiom of choice

2 votes
1 answer
226 views

Intermediate value theorem in topological spaces

2 votes
1 answer
158 views

The boundary point of every open set of a metric space is a limit point?

2 votes
2 answers
132 views

The rigorous definition of continuity in a topological space

2 votes
1 answer
42 views

Relation between the function image and function divergence

2 votes
2 answers
285 views

Logic - Proof of a resolution rule

2 votes
1 answer
851 views

Topology - Every injective quotient map is a homeomorphism

1 vote
2 answers
106 views

Logic - Reducing a first-order logic involving a material conditional

1 vote
0 answers
28 views

Set notation for an indexed family

1 vote
0 answers
135 views

Set inclusion: map image of inverse image