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José Carlos Santos

Porto, Portugal

http://www.fc.up.pt/mp/jcsantos/

I am a mathematician who works at the University of Porto (Portugal). My PhD, on Representation Theory, was obtained at the Université Paris — Denis Diderot, in 1996.

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Top Questions
172 votes

Why was "An Update to our Community and an Apology" deleted?

discussion meta deleted-questions stack-exchange-team censor asked Dec 24 '19 at 12:16
meta.stackexchange.com

116 votes

Unexpected examples of natural logarithm

soft-question logarithms big-list asked Jul 3 '17 at 13:07
math.stackexchange.com

51 votes

Proving $\left(1-\frac13+\frac15-\frac17+\cdots\right)^2=\frac38\left(\frac1{1^2}+\frac1{2^2}+\frac1{3^2}+\frac1{4^2}+\cdots\right)$

real-analysis sequences-and-series summation asked Oct 2 '17 at 10:17
math.stackexchange.com

49 votes

Why were the Allies so much better cryptanalysts?

world-war-two espionage cryptology secrecy asked Nov 22 '20 at 9:03
history.stackexchange.com

33 votes

In what way were Renaissance battles like chess matches?

middle-ages warfare renaissance reference asked Oct 29 '19 at 17:55
history.stackexchange.com

31 votes

Could a German insult Hitler without being arrested?

nazi-germany hitler asked Dec 15 '19 at 10:02
history.stackexchange.com

28 votes

Is every matrix conjugate to its transpose in a continuous way?

linear-algebra matrices continuity transpose similar-matrices asked Dec 14 '18 at 10:03
math.stackexchange.com

27 votes

How likely it is that a nobleman of the eighteenth century would give written instructions to his maids?

united-kingdom 18th-century education asked Jan 24 '21 at 12:00
history.stackexchange.com

26 votes

Change in the way the first posts review queue works?

support bug status-completed review asked Apr 15 '21 at 7:42
meta.stackexchange.com

21 votes

No more thanks for reviewing 20 posts from a review queue

bug status-completed review asked Sep 8 '21 at 16:00
meta.stackexchange.com

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Top Answers
154
Why not include as a requirement that all functions must be continuous to be differentiable?
math.stackexchange.com

88
How can a "proper" function have a vertical slope?
math.stackexchange.com

87
Can a binary operation have an identity element when it is not associative and commutative?
math.stackexchange.com

85
Does an increasing sequence of reals converge if the difference of consecutive terms approaches zero?
math.stackexchange.com

77
Unsolved Problems due to Lack of Computational Power
math.stackexchange.com

64
Why a $20$ digit number starting with eleven $1$'s cannot be a perfect square?
math.stackexchange.com

63
False proof that $ρe^{iθ} = ρ$ and so complex numbers do not exist?
math.stackexchange.com

55
What is an example of a sequence which "thins out" and is finite?
math.stackexchange.com

49
How many times do you have to use L'Hôpital's rule?
math.stackexchange.com

46
Can we use symmetry rules in improper integrals?
math.stackexchange.com

46
If derivative of $f$ is continuous, then $f$ is continuous.
math.stackexchange.com

46
How are the known digits of $\pi$ guaranteed?
math.stackexchange.com

45
Why is the notion of analytic function so important?
math.stackexchange.com

45
How to determine if a set of five $2\times2$ matrices is independent
math.stackexchange.com

42
Problem with estimating a sequence with intuition
math.stackexchange.com

42
A Simple Calculus view on Fermat's Last Theorem
math.stackexchange.com

40
Understandable questions which are hard for non-mathematicians but easy for mathematicians
math.stackexchange.com

39
Non abelian group which contains no abelian subgroup
math.stackexchange.com

38
Can the product of three complex numbers ever be real?
math.stackexchange.com

37
Integration of secant
math.stackexchange.com

36
Sets that are both Sum-free and Product-free
math.stackexchange.com

36
Cross product in higher dimensions
math.stackexchange.com

36
Are these square matrices always diagonalisable?
math.stackexchange.com

35
Finding the 10th root of a matrix
math.stackexchange.com

35
How could $\varnothing$ be unique if it could be vacuously false?
math.stackexchange.com

34
General request for a book on mathematical history, for a VERY advanced reader.
math.stackexchange.com

34
How to compute the determinant of this Toeplitz matrix?
math.stackexchange.com

33
What is the context for Napoleon's quote "[the Austrians] did not know the value of five minutes"?
history.stackexchange.com

33
Why does Zorn's Lemma fail to produce a largest group?
math.stackexchange.com

32
Story of a student who solves an open problem
hsm.stackexchange.com

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