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9 votes
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What is known about vector subspaces of polynomial rings closed under factors?

Let $R$ be a commutative ring. Call a nonempty subset $F$ of $R$ a factroid if it is closed under sums and factors. That is: If $a,b \in F$, then $a+b \in F$, and If $a,b \in R$ with $a\in R$ ...
Neil Epstein's user avatar
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5 votes
0 answers
66 views

weak factorization systems (co)generated by an arbitrary class of morphisms

Under what assumptions can one prove existence of weak factorization systems (co)generated by a class of morphisms ? Are there counterexamples ? I am interested both in assumptions on the class of ...
user494312's user avatar
4 votes
0 answers
119 views

Adjoining new factors for primes in UFDs

It is well-known that if we pass from a UFD to a new ring where we have factored one of the primes, it does not need to stay a UFD. The classic example is passing from $\mathbb{Z}$ to $\mathbb{Z}[\...
Pace Nielsen's user avatar
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4 votes
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216 views

Characterizing atomicity in a commutative domain

In Proposition 1.1 of [Math. Proc. Cambridge Phil. Soc. 64 (1968), No. 2, 251-264], P.M. Cohn famously claimed (without proof) that a commutative domain is atomic if and only if it satisfies the ...
Salvo Tringali's user avatar
2 votes
0 answers
140 views

Integers with exactly three factor pairs whose successors are relatively prime

I am interested in the following problem, and will appreciate pointers around how it can be solved – partially or fully – and/or indicators around whether it is even tractable: Characterize $N \in \...
Benjamin Dickman's user avatar
0 votes
0 answers
65 views

Reference Request: Factorization method for polynomials whose maximum absolute value of coefficient is 1

So, today I came up with a method for factoring polynomials whose coefficients are either $-1$ or $1.$ Let me explain with examples. Example No. 1. Factorize $P(x)=x^8+x^7+1$ Solution. It is known ...
Ivan Borisyuk's user avatar
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138 views

A diophantine equation involving partial sums of exponentials similar than the equation in Fermat's Last Theorem

I'm curious about the following diophantine equation from my invention: I don't know if this is in the literature, I wrote it using creativity in an attempt to write a variant of the equation in ...
user142929's user avatar