Abstract
For any sentenceα (in sentential logic) letd α be the delay complexity of the boolean functionf α represented byα. We prove that for infinitely manyd (and starting with somed<620) there exist valid implicationsα→β withd α,d β≦d such that any Craig's interpolantx has its delay complexityd χ greater thand+(1/3)·log(d/2). This is the first (non-trivial) known lower bound on the complexity of Craig's interpolants in sentential logic, whose general study may well have an impact on the central problems of computation theory.
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Mundici, D. A lower bound for the complexity of Craig's interpolants in sentential logic. Arch math Logik 23, 27–36 (1983). https://doi.org/10.1007/BF02023010
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DOI: https://doi.org/10.1007/BF02023010