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Oct
23
revised How do I figure out the value of a number raised to a fractional power?
added 82 characters in body
Oct
23
answered How do I figure out the value of a number raised to a fractional power?
Oct
16
comment Propositional Calculus: Stating and proving the unique readability theorem in Polish notation
"an initial segment of one another, which we know is not possible" I bet, that had to be proved as a lemma, ah?
Oct
14
comment Is this true: $\lim_{\lambda \rightarrow 0}E\left[ e^{-\lambda X} \right] = P\left(X < \infty \right)$?
I bet the OP meant $\lim_{\lambda \to 0}$
Oct
12
revised $(x+1)/x = \sqrt{3}$ in form $a+b \sqrt{3}$
edited body
Oct
12
comment $(x+1)/x = \sqrt{3}$ in form $a+b \sqrt{3}$
@columbus8myhw, thanks. Yes, even simple questions in maths can have deeper answers.
Oct
12
answered $(x+1)/x = \sqrt{3}$ in form $a+b \sqrt{3}$
Oct
2
comment Formula for the terms of the sequence defined by $a_0 = 1$, $a_1 = -2$ and $a_{n}=-4 a_{n-1}-4 a_{n-2}$
@Mark, induction is: show that the first domino falls, and that every domino that falls knocks the next one; then you can be sure all dominoes fall. Strong induction is, show that the first domino falls, and that if all dominoes up to a certain point fell, then the next one falls too. So, strong induction -although equivalent- allows you to use as argument a stronger assumption ("all dominoes up to a point") to prove that the next one also falls. Stronger assumptions make proofs easier.
Aug
27
comment Proof that group is commutative if every element is its inverse (feedback wanted)
Seems fine to me :)
Aug
26
comment Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
Your definition is different.
Aug
26
comment Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
If you check en.m.wikipedia.org/wiki/Infinite_set, what you want to prove is mentioned there and requires the axiom of choice.
Aug
26
comment Verify my proof: If $X$ is infinite, then there exists $f: \mathbb{N} \rightarrow X$ such that $f$ is injective.
What is your definition of infinite set?
Aug
25
revised The set of all finite subsets of the natural numbers is countable
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Aug
25
revised The set of all finite subsets of the natural numbers is countable
added 21 characters in body
Aug
25
awarded  Yearling
Aug
25
comment The set of all finite subsets of the natural numbers is countable
@GuilhermeD, I posted as answer comments of your proof. Hope helps.
Aug
25
answered The set of all finite subsets of the natural numbers is countable
Aug
25
comment The set of all finite subsets of the natural numbers is countable
@GuilhermeD - what is $A_n$ ?!
Aug
25
comment The set of all finite subsets of the natural numbers is countable
@GuilhermeD, I believe is easier if you invoke the binary representation of every natural number... but that is not approach.
Aug
25
comment The set of all finite subsets of the natural numbers is countable
@GuilhermeD, I may have a mistake. One can inject X into N, but turning that into a bijection may require more steps :(