Single page proof of Fermat's Last Theorem (a la Fermat) discovered and validated by 31/12/1999.
Standard ambiguity clause: If the wording is found to be ambiguous the Panel will judge on the basis of the obvious intent. If the intent is ambiguous the Panel will judge on the basis of precise wording. If both are ambiguous or if both are clear but conflict, the Panel will look for a solution that causes the least damage to FX as a market and game.
1) Length: We are willing to be somewhat flexible with regards to whether a proof can be considered "one page" or not, in order to avoid bickering about single vs double sided pages, font size etc.
2) "A la Fermat": the proof may only use mathematical results known at the time of Fermat's death. This means that any lemmas or post-Fermat theorems must be included in the length of the proof.
3) Validity: Considering the number of invalid FLT proofs that have been proposed in the past, the burden of proof has to lie with the author. The proof would have to be published in a refereed math journal. We're willing to make exceptions in the case of a proof which has not yet been officially published, but has gained widespread acceptance in the mathematics community. We may decide to postpone judging until it is clear the proof is not contested.
FAQ: some people have asked whether the "proof" at http://ourworld.compuserve.com/homepages/grok/fermat.htm would satisfy the claim. 1) It would be acceptable in terms of length. 2) It does not seem to use any post-Fermat results, however the lemma's would need to be included to calculate length. 3) It would need to be rewritten in somewhat more formal mathematical proof form, and someone on sci.math has already stated that it contains an error. Either way, it wouldn't satisfy the claim until publication or widespread acceptance.