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Jul
9
answered Suppose $a$ is a perfect square and $a \ge 9$. Prove that $a - 1$ is composite.
Jul
8
revised Proving that $aRb \iff a^2-b^2=a-b$ is an equivalence relation
edited title
Jul
7
revised Constructing a formule
edited tags
Jul
7
answered Why do people lose in chess?
Jul
7
comment Zermelo–Fraenkel set theory the natural numbers defines $1$ as $1 = \{\{\}\}$ but this does not seem right
I've never seen the point of view that formalization is essentially just expressing something in another language/symbolism, that's an interesting way of looking at it.
Jul
7
answered Zermelo–Fraenkel set theory the natural numbers defines $1$ as $1 = \{\{\}\}$ but this does not seem right
Jul
7
comment How do you compute the inverse of the following permutation?
Are you sure you can't compute the inverse? Do you understand the definition of "inverse"?
Jul
7
answered How to get the sides of a triangle within a larger triangle?
Jul
6
comment Possible Fields?
@user161978 "Cauchy sequence" doesn't mean anything in the context of an arbitrary field! What is the metric? (There is in fact one standard answer to this question, which is to require an absolute value and consider the induced metric).
Jul
6
comment Need help understanding a paragraph from a book
@Fermat True, but if you give the OP the impression that something called "series" are required to understand this, they'll google that, see the calculus stuff, and potentially get scared off (given their request to explain it using high-school math).
Jul
6
revised Fraction exponents in division
added 16 characters in body; edited tags
Jul
6
answered What kind of transformation an upper triangular matrix represents
Jul
6
comment Need help understanding a paragraph from a book
This is a finite sum, no series are required.
Jul
6
comment How many times can you round a number?
This doesn't answer the question. The question is about how many iterations it takes for a particular rounding algorithm to terminate.
Jul
5
answered Permutations of Objects on Grid
Jul
5
revised Permutations of Objects on Grid
edited tags
Jul
5
comment Bijection from $\mathbb{R}^n$ to $\mathbb{R}$ that preserves lexicographic order?
This is definitely not abstract algebra. I'd be tempted to tag it as topology, but I'm not sure.
Jul
5
comment Why is this proof of $\mathbb{N}\times\mathbb{N}$ being countable not formal?
Rigor is not a rigorously defined notion. It's a spectrum.
Jul
5
answered Does cofactor expansion generalize to complex matrices?
Jul
5
accepted History of $p$-adic numbers