Showing papers by "Alexander A. Razborov published in 1994"
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TL;DR: Every formal complexity measure which can prove super-polynomial lower bounds for a single function, can do so for almost all functions, which is one of the key requirements to a natural proof in the authors' sense.
Abstract: We introduce the notion ofnaturalproof. We argue that the known proofs of lower bounds on the complexity of explicit Boolean functions in nonmonotone models fall within our definition of natural. We show, based on a hardness assumption, that natural proofs can not prove superpolynomial lower bounds for general circuits. Without the hardness assumption, we are able to show that they can not prove exponential lower bounds (for general circuits) for the discrete logarithm problem. We show that the weaker class ofAC0-natural proofs which is sufficient to prove the parity lower bounds of Furst, Saxe, and Sipser, Yao, and Hastad is inherently incapable of proving the bounds of Razborov and Smolensky. We give some formal evidence that natural proofs are indeed natural by showing that every formal complexity measure, which can prove superpolynomial lower bounds for a single function, can do so for almost all functions, which is one of the two requirements of a natural proof in our sense.
296 citations
TL;DR: In this article, Razborov et al. studied disjoint NP-pairs representable in a theory T of Bounded Arithmetic in the sense that T proves U intersection V = \emptyset, and showed that such a separation is obvious for the theory S(S_2) + S Sigma^b_2 -PIND considered in [1].
Abstract: In this paper we study the pairs (U,V) of disjoint NP-sets representable in a theory T of Bounded Arithmetic in the sense that T proves U intersection V = \emptyset. For a large variety of theories T we exhibit a natural disjoint NP-pair which is complete for the class of disjoint NP-pairs representable in T. This allows us to clarify the approach to showing independence of central open questions in Boolean complexity from theories of Bounded Arithmetic initiated in [1]. Namely, in order to prove the independence result from a theory T, it is sufficient to separate the corresponding complete NP-pair by a (quasi)poly-time computable set. We remark that such a separation is obvious for the theory S(S_2) + S Sigma^b_2 - PIND considered in [1], and this gives an alternative proof of the main result from that paper. [1] A. Razborov. Unprovability of lower bounds on circuit size in certain fragments of Bounded Arithmetic. To appear in Izvestiya of the RAN , 1994.
116 citations
Journal Article•
TL;DR: This paper study the pairs (U,V) of disjoint NP-sets representable in a theory T of Bounded Arithmetic in the sense that T proves U intersection V = \emptyset, which allows the approach to showing independence of central open questions in Boolean complexity from theories of Bounding Arithmetic to be clarified.
Abstract: In this paper we study the pairs (U,V) of disjoint NP-sets representable in a theory T of Bounded Arithmetic in the sense that T proves U intersection V = \emptyset. For a large variety of theories T we exhibit a natural disjoint NP-pair which is complete for the class of disjoint NP-pairs representable in T. This allows us to clarify the approach to showing independence of central open questions in Boolean complexity from theories of Bounded Arithmetic initiated in [1]. Namely, in order to prove the independence result from a theory T, it is sufficient to separate the corresponding complete NP-pair by a (quasi)poly-time computable set. We remark that such a separation is obvious for the theory S(S_2) + S Sigma^b_2 - PIND considered in [1], and this gives an alternative proof of the main result from that paper. [1] A. Razborov. Unprovability of lower bounds on circuit size in certain fragments of Bounded Arithmetic. To appear in Izvestiya of the RAN , 1994.
37 citations