Logic

Is gravity running out of puff?
Gravity is running out of puff. One day, unless its continual accelerative force is replenished, gravity will disappear. Proof: Latest evidence shows that the universe is expanding faster and faster - gravity is disappearing. Next to disappear will be atoms and particles. Unless they continually make their p... 7 Dec 2009 08:28

ISRAELIs ATTACK FOR good REASON
In article <73djg51pb27jphkohcuv6vl8ku9uo2duin(a)4ax.com>, Give Our Taxes to Bankers for Free! on Hopes They'll Lend a Little Back MAYBE <lbmfflfmbflmfblfmblfmbf(a)hotmail.com> wrote: ISRAEL ATTACKS GAZA WITH WARPLANES!!! It's what warplanes are for. snicker. ... 24 Nov 2009 13:23

Another AC anomaly?
Has anyone seen this before? http://possiblyphilosophy.wordpress.com/2008/09/22/guessing-the-result-of-infinitely-many-coin-tosses/ I'm not sure yet what to conclude from it; that AC is horribly wrong, or that WM is horribly right, or something else altogether. In short the story goes like this: A game is... 27 Dec 2009 16:18

A new definition of Cardinality.
Hi all, As far as I know, all the definitions of cardinality have limited in a way or another, lets take them one after the other: 1) Von Neumann's Cardinals: A cardinal is the least of all equinumerous ordinals. 2) Frege-Russell Cardinals: A cardinal is an equivalence class of sets under equivalence re... 30 Nov 2009 21:25

Why (ex Elimination) so complicated? (SEP)
Dear All Just looking at the SEP natural deduction entry (*). I find the following existential elimination rule (slightly adapted, switching D and G): G |- Ex A D, A |- B ------------------------- (E E) (x not in D, B) D, G |- B Looks quite complicated to me. Why? I can instantiate... 21 Nov 2009 22:31

Wittgenstein. An analysis of syntax.
In the mature Witt. there is a split between logic and grammar, between syntax and organizing principle of the elements of syntax. It wasn't as Hinttika said - that Witt's major development (1929), was about changing from a phenomenological language to a physicalist one, but it was Witt's distinction that bore... 29 Nov 2009 00:28

Let us reduce the speed of light
If speed of light was not so high - 300,000 km/sec, what difference would we see? Would time travel be possible? Black holes sure be forming too frequently (off course without their devastating effects, since they wont be so massive then). ... 19 Nov 2009 18:37

Second Doubt
Hello William Elliot, and everybody else. I am reading "Introduction to mathematical logic", by Elliot Mendelson, and this is my doubt: First of all I must explain: In any proof, one wf depends upon other if the first one needs the presence of the second to achieve the proof. Then it comes deduction theorem: " Ass... 25 Nov 2009 03:48

Is ZF + CH + not-CC consistent?
Subject says it (CC stands for 'countable choice'). More generally, the question is: 'how much' of AxC is implied by CH? (As AC is equivalent to the trichotomy of cardinals, and CH imply trichotomy for sets not larger than P(N), someone might expect that ZF+CH perhaps implies some weak forms of choice.) --... 23 Nov 2009 01:59

P = NP in NY Times
http://www.nytimes.com/2009/10/08/science/Wpolynom.html?_r=1 How would algebraic geometry contribute to resolving this question? -- Rich ... 16 Nov 2009 16:56