Proof theory is a branch of mathematical logic that represents proofs as formal mathematical objects, facilitating their analysis by mathematical techniques. Proofs are typically presented as inductively-defined data structures such as plain lists, boxed lists, or trees, which are constructed according to the axioms and rules of inference of the logical system. As such, proof theory is syntactic in nature, in contrast to model theory, which is semantic in nature. Together with model theory, axiomatic set theory, and recursion theory, proof theory is one of the so-called four pillars of the foundations of mathematics.

Proof theory is important in philosophical logic, where the primary interest is in the idea of a proof-theoretic semantics, an idea which depends upon technical ideas in structural proof theory to be feasible.

From Wikipedia under the GNU Free Documentation License
Sun Nov 8 08:29:01 2009

product thumb php
kettcosmetics.com
product thumb php
100px x 150px | 12.80kB

[source page]

Color Theory Trial Packs $27 50

proof6 gif
science.uva.nl
proof6 gif
713px x 550px | 14.30kB

[source page]

proof The reader is encouraged to complete the proof as an exercise For those who would like to check their work we give the complete Proof of the General Principle of Induction here Proof Now to derive Principle of Mathematical Induction from the General Principle of Induction we formulate the instance of the latter in which a is 0 and R is Precedes F0

proof4 gif
science.uva.nl
proof4 gif
412px x 527px | 10.50kB

[source page]

xFx Proof Note that the proof appeals to Hume s Principle and facts about equinumerosity Frege s definition of the concept natural number can now be stated in terms of the weak

From Yahoo Image Search: "Proof Theory"
Sat Sep 19 20:29:08 2009

Worthwhile Canadian Initiative: A " proof " of Say's Law; and why ...
worthwhile.typepad.com
Worthwhile Canadian Initiative: A " proof " of Say's Law; and why ...

Nick Rowe

ue, 15 Sep 2009 05:00:23 GM

Not exactly mainstream . theory. (no offence intended to those groups). fourthtimeanon:​ but I did allow bonds to be one of the goods. Hence loans and leverage are not excluded from my ". proof. ". I agree on constant MV. ...

 Proof Theory
filedownloadfull.com
Proof Theory

admin

hu, 11 Jun 2009 11:35:05 GM

Gaisi Takeuti, ". Proof Theory. "Elsevier Science Ltd| 1987 | ISBN: 0444879439 | 500 pages | PDF | 22,3 MB From reader s review:Takeuti was undoubtedly one of the greatest logicians of the twentieth century and this book is indispensable ...

Math Pages Blog: Indescribable numbers
mathpages.blogspot.com
Math Pages Blog: Indescribable numbers

(Anatoly)

Fri, 18 Sep 2009 12:11:01 GM

Unfortunately, while this is a relatively well know term I frequently see it being misused. To understand it, we must firstly look on the . proof. that such numbers exist. It is a rather basic . proof. from set . theory. . ...

From Google Blog Search: "Proof Theory"
Sat Sep 19 20:32:35 2009

Health care: Not exactly recession-proof - Helena Independent Record
news.google.com
Health care: Not exactly recession- proof

Helena Independent Record

"In theory , we've always thought in this industry that we were recession- proof ," said Craig Aasved, chief operating officer for St. Patrick Hospital in ...



and more »
The Naked Truth: Fairfax man charged with indecent exposure in private home - Washington Post
news.google.com
The Naked Truth: Fairfax man charged with indecent exposure in private home

Washington Post

Atchuthan Sriskandarajah: Your theory has some merit. But the woman has not been charged with a crime. Bala Cynwyd, Pa. ...



and more »
Opting out: Not as simple as it looks - Politico
news.google.com
Opting out: Not as simple as it looks

Politico

When elected officials were searching for votes last week in favor of a filibuster- proof public option and appeared to come up short, Democratic Sens. ...



and more »

From Google News Search: "Proof Theory"
Fri Nov 6 09:49:47 2009

Is it still a "Conspiracy Theory" when the "Theorists" have proof?
Q. Proof of the "theory" being true.
Asked by True Aquarian - Thu Apr 3 14:10:34 2008 - - 17 Answers - 0 Comments

A. Yes. If you are an ignorant, brain-washed sheep of a person who's brain is so small you can't accept a different version of reality than the one you've had beaten in your head all your life. If you're dumbed down by drinking flouridated water, eating anti-depressants like candy and attending the state-controlled public school system. If you follow your leaders like a lost puppy because they lie to you and tell you, "Everything's going to be alright, we've had problems like this before". If you never read a book and instead spend your time watching the Orwellian mind-control device, our main stream media on the IDIOT box. If you're too stupid to realize that the elite of this world have always oppressed the masses for their own self-ser [cont.]
Answered by Bill and Carey S - Thu Apr 3 15:37:24 2008

"Interesting" numbers and the Hangman paradox in proof theory?
Q. First off, wikipedia gives a *decent* discussion of the hangman paradox. If you don't know it, you can find it here: Now, normally, we don't seem to care much about this paradox in mathematics, since there isn't even consensus on where the paradox originates from. However, it occurs to me that a standard proof that appears in mathematical literature may be an instance of this same paradox. --- Proof that all natural numbers are interesting: First, let N be the set of natural numbers and X the set of interesting natural numbers. We want to show that N is a subset of X. Suppose otherwise, that there is an element n of N that isn't interesting, then the set N\X is nonempty. Since N is well-ordered, N\X has a least element - call it y. [cont.]
Asked by Awms A - Mon Oct 13 21:59:19 2008 - - 1 Answers - 0 Comments

A. Long ago I thought I was interested in logic and philosophy. Now it puzzles me that I once felt that way. That was an interesting proof you gave (which I had seen before), but it reminded me that there are theorems about the length of proofs, so maybe there should be theorems about the interestingness (or not) of proofs. Well, I know nothing about proof theory, so can't possibly answer your question properly. All I can do is make a few comments. It seems to me the similarity to the interesting numbers proof may draw from the fact that there are multiple days in a week. If there are only two days in the week, then at least superficially it seems more like the Russell paradox, or the heterological paradox. And if you have only one day… [cont.]
Answered by JB - Mon Oct 13 22:44:50 2008

Why is it that science gets away on ideas and theory with out any real proof but they want proof of God?
Q. Arcealogys dug up a seal of the prince that put the prophet Jeremiah down the well. Ancient Greek wrote about the beheading of John the Baptist. There have been so many things that prove the Bible is historically accurate. What more do you need? Would you believe if you saw a miracle
Asked by wammer jammer - Thu Aug 14 22:29:31 2008 - - 34 Answers - 0 Comments

A. Did the Pharisees and Sadducees believe when they saw mighty miracles? Did the multitudes who followed Christ to get their bellies filled and witness His power stay with Him when the preached word became too difficult to hear? No, they did not. Did you come into the kingdom by the physical evidence you see around you (which is faithless by the way), or did you enter into the kingdom by hearing the preached word and repenting and believing from your heart? Faith by its very definition is rooted in that which we can't see, so why do you demand atheists believe on nothing more than physical evidence. Since the things we see are so temporal and fluctuate daily, wouldn't our faith be a tenuous thing indeed if it were based on the sort of… [cont.]
Answered by Elizabeth L - Thu Aug 14 22:46:22 2008

From Yahoo Answer Search: "Proof Theory"
Thu Nov 19 18:20:14 2009

See also:

  • The Calculus of StructuresThe Calculus of Structures
    alessio.guglielmi.name
    The calculus of structures is a new proof theoretical formalism. It exploits a top-down symmetry of derivations made possible by deep inference.
  • G. Japaridze's PapersG. Japaridze's Papers
    csc.villanova.edu
    Full list of publications by this author, with about 30 items in the area of proof theory. Many of the papers are downloadable.
  • Proof TheoryProof Theory
    open-site.org
    Open Encyclopedia entry. Hierarchically organized by subtopics.
Custom search only Proof Theory sites:

Help build the largest human-edited directory on the web.
Submit a Site - Open Directory Project - Become an Editor
Sat Nov 7 12:04:39 2009