11,657 reputation
1535
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location Turin, Italy
age 53
visits member for 3 years, 8 months
seen 8 hours ago

15h
answered How to find a primitive element of $\mathbb{Q}(\sqrt{2}, \sqrt{3}, \sqrt{5})$ over $\mathbb{Q}$?
23h
comment can any one help me with this pigeonhole question?
Actually, he said how far he got: "I have no clue".
23h
comment One question about open sets in topology
I believe that the shaded sentence is the definition of open set in a metric space
1d
comment valuation ring is a field?
Ok, so $k=x$, then what? Mind that $a/a=b/b=1\in B$ is true for every domain.
1d
comment valuation ring is a field?
You have lots of "$k=..$ then $x$ such and such". What's the relation between $k$ and $x$?
Apr
10
answered Show that $(\mathbb{Q}^*,\cdot)$ and $(\mathbb{R}^*,\cdot)$ aren't cyclic
Apr
9
answered Proof for value of sum of sine and cosine
Apr
9
comment Proof for value of sum of sine and cosine
oh my! :) bad notation!
Apr
9
comment Proof for value of sum of sine and cosine
The questioner has the imaginary unit $i$ in the argument of the trig functions ....
Apr
9
comment Proof for value of sum of sine and cosine
sine and cosine
Apr
2
comment “Primeness” of C[x] in B[x], where A is a subring of B and C is the integral closure of A in B.
I think you need monic polynomials, otherwise the shadowed claim seems to be false (take $A=\Bbb Z$, $B=\Bbb Q$ and $f=2$, $g=1/2$-- constant polynomials)
Mar
31
answered Analogy between the quaternion ring and extensions of the rationals
Mar
30
answered Which kind of derivative give $D e^{xy}=e^{xy}$?
Mar
29
answered Let $R$ be a field. What are the $R$-submodules of $R \times R \ ?$
Mar
29
revised Factorising ideals in $\mathbb{Z}[\sqrt{10}]$
edited body
Mar
29
answered Factorising ideals in $\mathbb{Z}[\sqrt{10}]$
Mar
29
answered Closed sets in Zariski Topology
Mar
29
comment Subfields of finite fields
As I said, the polynomial $X^{p^s}-X$ divides $X^{p^r}-X$, thus the roots of the former (elements of ${\Bbb F}_{p^s}$) are also roots of the latter (elements of ${\Bbb F}_{p^r}$)
Mar
24
revised Zero dimensional local ring with maximal ideal not principal.
deleted 2 characters in body
Mar
24
revised Zero dimensional local ring with maximal ideal not principal.
added 2 characters in body