"Clarithmetic" is a generic name for formal number theories similar to Peano arithmetic, but based on computability logic instead of the more traditional classical or intuitionistic logics. Formulas of clari...
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"Clarithmetic" is a generic name for formal number theories similar to Peano arithmetic, but based on computability logic instead of the more traditional classical or intuitionistic logics. Formulas of clarithmetical theories represent interactive computational problems, and their "truth" is understood as existence of an algorithmic solution. Imposing various complexity constraints on such solutions yields various versions of clarithmetic. The present paper introduces a system of clarithmetic for polynomial time computability, which is shown to be sound and complete. Sound in the sense that every theorem T of the system represents an interactive number-theoretic computational problem with a polynomial time solution and, furthermore, such a solution can be efficiently extracted from a proof of T. And complete in the sense that every interactive number-theoretic problem with a polynomial time solution is represented by some theorem T of the system. The paper is written in a semitutorial style and targets readers with no prior familiarity with computability logic. (C) 2011 Elsevier Inc. All rights reserved.
A system of linear dependent types for the lambda calculus with full higher-order recursion, called dlPCF, is introduced and proved sound and relatively complete. Completeness holds in a strong sense: dlPCF is not onl...
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ISBN:
(纸本)9780769544120
A system of linear dependent types for the lambda calculus with full higher-order recursion, called dlPCF, is introduced and proved sound and relatively complete. Completeness holds in a strong sense: dlPCF is not only able to precisely capture the functional behaviour of P C F programs (i.e. how the output relates to the input) but also some of their intensional properties, namely the complexity of evaluating them with Krivine's Machine. dlPCF is designed around dependent types and linear logic and is parametrized on the underlying language of index terms, which can be tuned so as to sacrifice completeness for tractability.
In this paper we present a new path order for rewrite systems, the exponential path order EPO*. Suppose a term rewrite system is compatible with EPO*, then the runtime complexity of this rewrite system is bounded from...
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ISBN:
(纸本)9783939897309
In this paper we present a new path order for rewrite systems, the exponential path order EPO*. Suppose a term rewrite system is compatible with EPO*, then the runtime complexity of this rewrite system is bounded from above by an exponential function. Furthermore, the class of function computed by a rewrite system compatible with EPO* equals the class of functions computable in exponential time on a Turing machine.
We propose a type system for an imperative programming language, which certifies program time bounds. This type system is based on secure flow information analysis. Each program variable has a level and we prevent inf...
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ISBN:
(纸本)9780769544120
We propose a type system for an imperative programming language, which certifies program time bounds. This type system is based on secure flow information analysis. Each program variable has a level and we prevent information from flowing from low level to higher level variables. We also introduce a downgrading mechanism in order to delineate a broader class of programs. Thus, we propose a relation between security-typed language and implicit computational complexity. We establish a characterization of the class of polynomial time functions.
In this contribution, we propose to study the transformation of first order programs by course of value recursion. Our motivation is to show that this transformation provides a separation criterion for the intentional...
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Ramified recurrence over free algebras has been used over the last two decades to provide machine-independent characterizations of major complexity classes. We consider here ramification for the dual setting, referrin...
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Ramified recurrence over free algebras has been used over the last two decades to provide machine-independent characterizations of major complexity classes. We consider here ramification for the dual setting, referring to coinductive data and corecurrence rather than inductive data and recurrence. Whereas ramified recurrence is related basically to feasible time (PTime) complexity, we show here that ramified corecurrence is related fundamentally to feasible space. Indeed, the 2-tier ramified corecursive functions are precisely the functions over streams computable in logarithmic space. Here we define the complexity of computing over streams in terms of the output rather than the input, i.e. the complexity of computing the n-th entry of the output as a function of n. The class of stream functions computable in logspace seems to be of independent interest, both theoretical and practical. We show that a stream function is definable by ramified corecurrence in two tiers iff it is computable by a transducer on streams that operates in space logarithmic in the position of the output symbol being computed. A consequence is that the two-tier ramified corecursive functions over finite streams are precisely the logspace functions, in the usual sense.
Various simplified or improved, and partly corrected well-known implicit characterizations of the complexity classes FPTIME and NC are presented. Primarily, the interest is in simplifying the required simulations of v...
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Various simplified or improved, and partly corrected well-known implicit characterizations of the complexity classes FPTIME and NC are presented. Primarily, the interest is in simplifying the required simulations of various recursion schemes in the corresponding (implicit) framework, and in developing those simulations in a more uniform way, based on a step-by-step comparison technique, thus consolidating groundwork in implicit computational complexity. (C) 2009 Elsevier Inc. All rights reserved.
We define realizability semantics for Light Affine Logic (LAL) which has the property that denotations of functions are polynomial time computable by construction of the model. This gives a new proof of polytime-sound...
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We define realizability semantics for Light Affine Logic (LAL) which has the property that denotations of functions are polynomial time computable by construction of the model. This gives a new proof of polytime-soundness of LAL which is considerably simpler than the standard proof based on proof nets and is entirely semantical in nature. The model construction uses a new instance of a resource monoid;a general method for interpreting systems based on Linear Logic introduced earlier by the authors.
We give a new characterization of elementary and deterministic polynomial time computation in linear logic through the proofs-as-programs correspondence. Girard's seminal results, concerning elementary and light l...
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We give a new characterization of elementary and deterministic polynomial time computation in linear logic through the proofs-as-programs correspondence. Girard's seminal results, concerning elementary and light linear logic, achieve this characterization by enforcing a stratification principle on proofs, using the notion of depth in proof nets. Here, we propose a more general form of stratification, based on inducing levels in proof nets by means of indices, which allows us to extend Girard's systems while keeping the same complexity properties. In particular, it turns out that Girard's systems can be recovered by forcing depth and level to coincide. A consequence of the higher flexibility of levels with respect to depth is the absence of boxes for handling the paragraph modality. We use this fact to propose a variant of our polytime system in which the paragraph modality is only allowed on atoms, and which may thus serve as a basis for developing lambda-calculus type assignment systems with more efficient typing algorithms than existing ones. (C) 2009 Elsevier B.V. All rights reserved.
We present a polymorphic type system for lambda calculus ensuring that well-typed programs can be executed in polynomial time: dual light affine logic (DLAL). DLAL has a simple type language with a linear and an intui...
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We present a polymorphic type system for lambda calculus ensuring that well-typed programs can be executed in polynomial time: dual light affine logic (DLAL). DLAL has a simple type language with a linear and an intuitionistic type arrow, and one modality. It corresponds to a fragment of light affine logic (LAL). We show that contrarily to LAL, DLAL ensures good properties on lambda-terms (and not only on proof-nets): subject reduction is satisfied and a well-typed term admits a polynomial bound on the length of any of its beta reduction sequences. We also give a translation of LAL into DLAL and deduce from it that all polynomial time functions can be represented in DLAL. (c) 2008 Elsevier Inc. All rights reserved.
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