Stephen Bellantoni and Stephen Cook. A new recursion-theoretic characterization of the polytime functions. Computational complexity, vol. 2 (1992), pp. 97–110. - Arnold Beckmann and Andreas Weiermann. A term rewriting characterization of the polytime functions and related complexity classes. Archive for mathematical logic, vol. 36 (1996), pp. 11–30.

2000 ◽  
Vol 6 (3) ◽  
pp. 351-353
Author(s):  
Karl-Heinz Niggl
1977 ◽  
Vol 42 (4) ◽  
pp. 545-563 ◽  
Author(s):  
Robert I. Soare

One of the most interesting aspects of the theory of computational complexity is the speed-up phenomenon such as the theorem of Blum [6, p. 326] which asserts the existence of a 0, 1-valued total recursive function with arbitrarily large speed-up. Blum and Marques [10] extended the speed-up definitions from total to partial recursive functions, or equivalently, to recursively enumerable (r.e.) sets, and introduced speedable and levelable sets. They classified the effectively speedable sets as the subcreative sets but remarked that “the characterizations we provided for speedable and levelable sets do not seem to bear a close relationship to any already well-studied class of recursively enumerable sets.” The purpose of this paper is to give an “information theoretic” characterization of speedable and levelable sets in terms of index sets resembling the jump operator. From these characterizations we derive numerous consequences about the degrees and structure of speedable and levelable sets.


1994 ◽  
Vol 59 (4) ◽  
pp. 1274-1284 ◽  
Author(s):  
Gaisi Takeuti

A proof-theoretic characterization of the primitive recursive functions is the Σ1-definable functions in IΣ1 as is shown in Mints [4], Parsons [5], and [8].Then what is a proof-theoretic characterization of Grzegorzyk's hierarchy? First we discuss a related previous work. In Clote and Takeuti [2], we introduced a theory TAC that corresponds to the computational complexity class AC. TAC has a very weak form of induction. We assign a rank to a proof in TAC in the following way. The rank of a proof P in TAC is the nesting number of inductions used in P. Then TACi is defined to be the subtheory of TAC whose proof has a rank ≤ i. We proved that TACi corresponds to the class ACi.In this paper we introduce a theory IepΣ1 which is equivalent to IΣ1. Then we define the rank of a proof in IepΣ1 as the nesting number of inductions in the proof and prove that the proofs with rank ≤ i correspond to Grzegorcyk's hierarchy for i > 0.We also prove that the system that has proofs with rank 0 is actually equivalent to I Δ0. These facts are interesting since it is proved in [10] that the theory isomorphic to TAC∘ by RSUV isomorphism is a conservative extension of I Δo. Therefore there is some analogy between the class AC and the primitive recursive functions.


1987 ◽  
Vol 10 (1) ◽  
pp. 1-33
Author(s):  
Egon Börger ◽  
Ulrich Löwen

We survey and give new results on logical characterizations of complexity classes in terms of the computational complexity of decision problems of various classes of logical formulas. There are two main approaches to obtain such results: The first approach yields logical descriptions of complexity classes by semantic restrictions (to e.g. finite structures) together with syntactic enrichment of logic by new expressive means (like e.g. fixed point operators). The second approach characterizes complexity classes by (the decision problem of) classes of formulas determined by purely syntactic restrictions on the formation of formulas.


Author(s):  
M. Ferrara ◽  
M. Trombetti

AbstractLet G be an abelian group. The aim of this short paper is to describe a way to identify pure subgroups H of G by looking only at how the subgroup lattice $$\mathcal {L}(H)$$ L ( H ) embeds in $$\mathcal {L}(G)$$ L ( G ) . It is worth noticing that all results are carried out in a local nilpotent context for a general definition of purity.


2021 ◽  
Vol 31 (3) ◽  
pp. 033107
Author(s):  
F. R. Iaconis ◽  
A. A. Jiménez Gandica ◽  
J. A. Del Punta ◽  
C. A. Delrieux ◽  
G. Gasaneo

2018 ◽  
Vol 61 (1) ◽  
pp. 166-173
Author(s):  
Cleto B. Miranda-Neto

AbstractIn this note we prove the following surprising characterization: if X ⊂ is an (embedded, non-empty, proper) algebraic variety deûned over a field k of characteristic zero, then X is a hypersurface if and only if the module of logarithmic vector fields of X is a reflexive -module. As a consequence of this result, we derive that if is a free -module, which is shown to be equivalent to the freeness of the t-th exterior power of for some (in fact, any) t ≤ n, then necessarily X is a Saito free divisor.


2011 ◽  
Vol 07 (01) ◽  
pp. 173-202
Author(s):  
ROBERT CARLS

In this article, we give a Galois-theoretic characterization of the canonical theta structure. The Galois property of the canonical theta structure translates into certain p-adic theta relations which are satisfied by the canonical theta null point of the canonical lift. As an application, we prove some 2-adic theta identities which describe the set of canonical theta null points of the canonical lifts of ordinary abelian varieties in characteristic 2. The latter theta relations are suitable for explicit canonical lifting. Using the theory of canonical theta null points, we are able to give a theoretical foundation to Mestre's point counting algorithm which is based on the computation of the generalized arithmetic geometric mean sequence.


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