Forcing in Nite Structures
نویسنده
چکیده
We present a simple and completely model-theoretical proof of a strengthening of a theorem of Ajtai's: the independence of the pigeonhole principle from I 0 (R). Qua strength, the theorem proved here corresponds to the complexity/proof-theoretical results of 10] and 14] but a diierent combinatorics is used. Techniques inspired by Razborov 11] replace those derived from H astad 8]. This leads to a much shorter and very direct construction.
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