1,478 reputation
16
bio website fkraiem.org
location Bordeaux, France
age
visits member for 7 months
seen Jul 22 at 10:57

Jun
24
comment Two conditions, necessary and sufficient conditions.
This is probably a mistranslation, but as written in English your second and third statements don't make sense. A range is just a mathematical object, and by itself can't be a condition for anything. A condition has to be a statement about an object.
Jun
6
awarded  Enthusiast
May
30
comment How to tell if a set is cyclic
What's a cyclic set? ;) (What you mean is a periodic sequence.)
May
28
answered How many different bases in $\mathbb{Z}/p\mathbb{Z}$
May
26
comment Recursive relationship
1. Compute $b_0$, $b_1$, $b_2$, etc. until you can make a conjecture. 2. Prove your conjecture, for example by induction.
May
23
comment Binomial Theorem on a Ring with Order 2
You could express $n$ as a power of $2$ times an odd number, but that's probably not going to give you something very pretty. However, $(a+b)^2 = a^2+b^2$ (and its analogues in any prime characteristic) is very important.
May
23
comment Binomial Theorem on a Ring with Order 2
What you mean is characteristic, not "order". A hint, see what happens for $(a+b)^2$, and try to extrapolate from there.
May
22
answered coding and decoding message with RSA.
May
22
comment coding and decoding message with RSA.
Again, $\phi(n) = (p-1)(q-1)$ only works if $p$ and $q$ are two distinct primes. Otherwise, it has some other value. See en.wikipedia.org/wiki/Euler%27s_totient_function
May
22
comment coding and decoding message with RSA.
Indeed, Alice will not be able to decrypt this message, because she used a public exponent which is not relatively prime with $\phi(n) = 1872$.
May
22
comment coding and decoding message with RSA.
Yes, it does, because $\phi(pq) = (p-1)(q-1)$ only works if $p$ and $q$ are distinct primes.
May
22
comment coding and decoding message with RSA.
$63 = 9\times 7$ is not prime!
May
22
comment Finding ideals in the ring $\mathbf{Z}_{12}$
Check which ones of those satisfy the second part of the definition of an ideal, which is... ?
May
22
comment Finding ideals in the ring $\mathbf{Z}_{12}$
Yes, that is it.
May
22
comment Finding ideals in the ring $\mathbf{Z}_{12}$
Well, first thing to be an ideal is to be a subgroup. What are the subgroups of $\mathbf{Z}_{12}$?
May
22
comment Can we define the normal set without $G$ being a group?
$X$ is not just any set, it is a subset of $G$. Otherwise, $gxg^{-1}$ doesn't make sense.
May
22
comment Very good linear algebra book.
@user1551 Lang's Intro. to Linear Algebra and Linear Algebra are different.
May
21
comment exclusive or logic truth table - not understanding why it is the way it is
You said it yourself: if $P$ and $Q$ are both true, then $P+Q$ is false...
May
19
comment Prove by induction that (5^(n))-1 is divisible by 4 for all natural numbers n.
Or alternatively, $5^{k+1}-1 = 5\times 5^k - 1 = 4\times 5^k + 5^k - 1$.
May
19
comment Factorizing degree four polynomial
This method only works if you know a root (the value of $a$). ;)