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Paolo's user avatar
Paolo
  • Member for 8 years, 10 months
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6 votes
1 answer
550 views

Homotopy type of the complement of a subspace

3 votes
2 answers
281 views

Rigid motions taking a regular $n$-gon back to itself carry vertices to vertices

3 votes
1 answer
71 views

Does $a^2(x) = b^2(x) (1 - x^2)$ imply $a = b = 0$?

3 votes
2 answers
881 views

A finite set and the set of its fixed points under any involution have cardinalities of the same parity

3 votes
3 answers
2k views

Limit of derivative does not exist, while limit of difference quotient is infinite

2 votes
2 answers
215 views

Necessary and sufficient condition for the union of two intervals to be an interval

2 votes
1 answer
1k views

Sufficient condition for inflection point

2 votes
1 answer
818 views

Arithmetic mean, geometric mean and definite integral

2 votes
0 answers
235 views

Exercise about retract of $GL(n, \mathbb{C})$ homeomorphic to $S^1$

2 votes
1 answer
295 views

Geometric transformations in Olympiad problems - Putnam 2001, A-4

1 vote
1 answer
145 views

Condition for the union of two affine subspaces to be an affine subspace

1 vote
1 answer
167 views

Numer of binary digits of a power of ten (from Weissman's “An Illustrated Theory of Numbers”)

1 vote
3 answers
76 views

Evaluate $\displaystyle\lim_{x \to 0^{-}} \frac{\sqrt{x^2 + x + 4} - 2}{\ln(1 + x + x^2) - x}$

1 vote
1 answer
121 views

Binary expansion of a positive integer and its half

1 vote
1 answer
761 views

Maxima, minima and contour diagrams

1 vote
0 answers
260 views

Sufficient condition for absolute maximum

1 vote
2 answers
37 views

"Four Is Not Enough" and distance between two sets

0 votes
0 answers
148 views

Cauchy sequences: equivalent condition using minimum

0 votes
1 answer
62 views

Exercise about intervals of the real line