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seen Sep 26 at 10:37

Jul
26
answered Proving the properties of big union of unions for indexed sets
Jul
26
comment If the same message is sent to Alice and Bob who are using different public keys, how can somoene following the channel find $m$
It's just an application of CRT. We know that $N_1$ and $N_2$ are relative prime. Then, for the given sequence of integers $c_1, c_2$, there exists an integer $x$ solving the system of the following simultaneous congruences: $x \equiv c_1\pmod {N_1}$ and $x \equiv c_2\pmod {N_2}$.
Jul
26
revised If the same message is sent to Alice and Bob who are using different public keys, how can somoene following the channel find $m$
added 1 character in body
Jul
26
answered If the same message is sent to Alice and Bob who are using different public keys, how can somoene following the channel find $m$
Jul
26
answered Need help with checking my proof related to equivalence mod n.
Jul
2
awarded  Curious
Mar
15
awarded  Notable Question
Feb
11
awarded  Notable Question
Jan
9
awarded  Citizen Patrol
Sep
25
awarded  Popular Question
Sep
2
accepted A proof by contradiction
Sep
2
accepted Is $3^n - 2^n$ composite for all integers $n \geq 6$?
Sep
2
accepted Is there a relation which is neither symmetric nor antisymmetric?
Sep
1
accepted Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$
Sep
1
comment Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$
Nice answer! Any tip on how you came up with this $z$?
Sep
1
comment Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$
Suppose $D_r$ and $D_s$ are both relations on $\mathbb{R}$. Then $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ \exists z \in \mathbb{R}((x,z) \in D_s \text{ and } (z,y) \in D_r) \}$
Sep
1
asked Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$
Aug
24
comment Is it true that $\forall b \forall c \forall x ((x^2 + bx + c \neq 0) \rightarrow b^2 - 4c < 0)$?
Great answers! Thanks, I understand now.
Aug
24
comment Is it true that $\forall b \forall c \forall x ((x^2 + bx + c \neq 0) \rightarrow b^2 - 4c < 0)$?
Yes, your answer helped a lot. Is it true that if $\forall b,c,x.\ P(b,c,x) \to Q(b,c)$ then $\forall b,c.\ (\forall x.\ P(b,c,x)) \to Q(b,c)$? How can we prove that they are not equivalent? Any hint?
Aug
24
accepted Is it true that $\forall b \forall c \forall x ((x^2 + bx + c \neq 0) \rightarrow b^2 - 4c < 0)$?