Recent content by Marcaias
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Graduate Is axiom of choice applicationless?
Ahh, thank you.- Marcaias
- Post #20
- Forum: Set Theory, Logic, Probability, Statistics
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Graduate Is axiom of choice applicationless?
Whoa, a theorem in what? Gödel showed it is not a theorem in ZF, and neither is its negation (assuming ZF is consistent, of course.)- Marcaias
- Post #13
- Forum: Set Theory, Logic, Probability, Statistics
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Graduate Is axiom of choice applicationless?
From Wikipedia:- Marcaias
- Post #11
- Forum: Set Theory, Logic, Probability, Statistics
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Graduate Can Any Inner Product Be Defined in Infinite Dimensional Vector Spaces?
First of all, a Hilbert space by definition must have an inner product defined on it. (A Hilbert space is a vector space over the real or complex numbers with a complete inner product.) Secondly, in a finite-dimensional space, if you fix any positive-definite matrix M, then the expression...- Marcaias
- Post #2
- Forum: Linear and Abstract Algebra
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Undergrad Find P.Q & Q.P from Permutations of X (1,2,3,4,5)
"Q=2 3 4 1 5" means that this mapping happens: \begin{tabular}{ | c | c | c | c | c | } \hline 1 & 2 & 3 & 4 & 5 \\ \Downarrow & \Downarrow & \Downarrow & \Downarrow & \Downarrow \\ 2 & 3 & 4 & 1 & 5 \\ \hline \end{tabular} In other words: 1 gets mapped to 2, 2...- Marcaias
- Post #2
- Forum: Linear and Abstract Algebra
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Graduate How does ZF fixes Russell's paradox?
It's not that there's an axiom in ZF explicitly preventing Russell's Paradox, but rather ZF *doesn't* include the axiom of comprehension, which is the cause of all the trouble. Instead, it only allows for sets to be "built from" other sets, by union, by image under a function, by power set, and...- Marcaias
- Post #2
- Forum: Set Theory, Logic, Probability, Statistics
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Does a tree exist if no one is there to observe it?
If you intend your interpretation to be predictive in the slightest, you still need to apply the usual probabilistic Rules of Quantum Mechanics at some point or you end up simply engaging in philosophical onanism. And the fact will remain that what you call Nature probabilistically choosing a...- Marcaias
- Post #15
- Forum: General Discussion
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Does a tree exist if no one is there to observe it?
If any of the people who told you "the tree doesn't even exist if we aren't around to observe it" are physicists, please smack them for me. :) To expand on what I meant... In quantum computing, it's called the "principle of deferred measurement." I believe it to be the fundamental paradox in...- Marcaias
- Post #7
- Forum: General Discussion
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Does a tree exist if no one is there to observe it?
Of course not! However, the behaviour of the system is exactly the same as if all the "observations" made by the tree, the grass, the wildlife, and so on were instead made by you when you stumbled into the forest a year later.- Marcaias
- Post #3
- Forum: General Discussion
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Pulsed electromagnetic field therapy (PEMF therapy)
You're not my dad. Nonetheless, done.- Marcaias
- Post #10
- Forum: Biology and Medical
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Pulsed electromagnetic field therapy (PEMF therapy)
So, I dug up some literature. Some good: Rats love it: So do strippers: And computer programmers: And it does seem to relieve some types of chronic pain: Surprise, though, it's not a cure-all: Dogs also seemed unimpressed: So, the websites selling this stuff...- Marcaias
- Post #8
- Forum: Biology and Medical
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Pulsed electromagnetic field therapy (PEMF therapy)
You have a Master's of Art degree in Physics.- Marcaias
- Post #4
- Forum: Biology and Medical
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Graduate Could space-time be a property of matter in string theory?
Wouldn't this correspond (roughly) to the Heisenberg picture of QM: fixed states with evolving positions and momenta?- Marcaias
- Post #2
- Forum: Quantum Physics
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Graduate Do Non-Associative Groups Exist and What Are Their Applications?
A group's operation is associative by definition. If you take out the associativity axiom, you get what's (apparently) called a loop. If you also remove the need for an identity, you get a quasigroup. This page on Wikipedia has a nice little table of what you call groups minus this or that...- Marcaias
- Post #3
- Forum: Linear and Abstract Algebra
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Undergrad Relation between rank and number of non-zero eigen values.
By the way, you don't even need the hermitian property. The same argument works for any diagonalizable matrix A.- Marcaias
- Post #11
- Forum: Linear and Abstract Algebra