Polynomial time ultrapowers and the consistency of circuit lower bounds
A polynomial time ultrapower is a structure given by the set of polynomial time computable functions modulo some ultrafilter. They model the universal theory ∀ PV of all polynomial time functions. Generalizing a theorem of Hirschfeld (Israel J Math 20(2):111–126, 1975 ), we show that every countable...
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| Vydáno v: | Archive for mathematical logic Ročník 59; číslo 1-2; s. 127 - 147 |
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| Hlavní autoři: | , |
| Médium: | Journal Article Publikace |
| Jazyk: | angličtina |
| Vydáno: |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.02.2020
Springer Nature B.V |
| Témata: | |
| ISSN: | 0933-5846, 1432-0665 |
| On-line přístup: | Získat plný text |
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| Shrnutí: | A polynomial time ultrapower is a structure given by the set of polynomial time computable functions modulo some ultrafilter. They model the universal theory
∀
PV
of all polynomial time functions. Generalizing a theorem of Hirschfeld (Israel J Math 20(2):111–126,
1975
), we show that every countable model of
∀
PV
is isomorphic to an existentially closed substructure of a polynomial time ultrapower. Moreover, one can take a substructure of a special form, namely a
limit
polynomial time ultrapower in the classical sense of Keisler (in: Bergelson, V., Blass, A., Di Nasso, M., Jin, R. (eds.) Ultrafilters across mathematics, contemporary mathematics vol 530, pp 163–179. AMS, New York,
1963
). Using a polynomial time ultrapower over a nonstandard Herbrand saturated model of
∀
PV
we show that
∀
PV
is consistent with a formal statement of a polynomial size circuit lower bound for a polynomial time computable function. This improves upon a recent result of Krajíček and Oliveira (Logical methods in computer science 13 (1:4),
2017
). |
|---|---|
| Bibliografie: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0933-5846 1432-0665 |
| DOI: | 10.1007/s00153-019-00681-y |