Applying Gödel's Dialectica Interpretation to Obtain a Constructive Proof of Higman's Lemma
نویسنده
چکیده
We use Gödel's Dialectica interpretation to analyse Nash-Williams' elegant but non-constructive 'minimal bad sequence' proof of Higman's Lemma. The result is a concise constructive proof of the lemma (for arbitrary decidable well-quasi-orders) in which Nash-Williams' combinatorial idea is clearly present, along with an explicit program for finding an embedded pair in sequences of words.
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