45,454 research outputs found
Build your own clarithmetic I: Setup and completeness
Clarithmetics are number theories based on computability logic (see
http://www.csc.villanova.edu/~japaridz/CL/ ). Formulas of these theories
represent interactive computational problems, and their "truth" is understood
as existence of an algorithmic solution. Various complexity constraints on such
solutions induce various versions of clarithmetic. The present paper introduces
a parameterized/schematic version CLA11(P1,P2,P3,P4). By tuning the three
parameters P1,P2,P3 in an essentially mechanical manner, one automatically
obtains sound and complete theories with respect to a wide range of target
tricomplexity classes, i.e. combinations of time (set by P3), space (set by P2)
and so called amplitude (set by P1) complexities. Sound in the sense that every
theorem T of the system represents an interactive number-theoretic
computational problem with a solution from the given tricomplexity class and,
furthermore, such a solution can be automatically extracted from a proof of T.
And complete in the sense that every interactive number-theoretic problem with
a solution from the given tricomplexity class is represented by some theorem of
the system. Furthermore, through tuning the 4th parameter P4, at the cost of
sacrificing recursive axiomatizability but not simplicity or elegance, the
above extensional completeness can be strengthened to intensional completeness,
according to which every formula representing a problem with a solution from
the given tricomplexity class is a theorem of the system. This article is
published in two parts. The present Part I introduces the system and proves its
completeness, while Part II is devoted to proving soundness
Introduction to clarithmetic I
"Clarithmetic" is a generic name for formal number theories similar to Peano
arithmetic, but based on computability logic (see
http://www.cis.upenn.edu/~giorgi/cl.html) 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
Ptarithmetic
The present article introduces ptarithmetic (short for "polynomial time
arithmetic") -- a formal number theory similar to the well known Peano
arithmetic, but based on the recently born computability logic (see
http://www.cis.upenn.edu/~giorgi/cl.html) instead of classical logic. The
formulas of ptarithmetic represent interactive computational problems rather
than just true/false statements, and their "truth" is understood as existence
of a polynomial time solution. The system of ptarithmetic elaborated in this
article 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 effectively 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 self-contained, and can be read without any previous familiarity
with computability logic.Comment: Substantially better versions are on their way. Hence the present
article probably will not be publishe
Model checking coalitional games in shortage resource scenarios
Verification of multi-agents systems (MAS) has been recently studied taking
into account the need of expressing resource bounds. Several logics for
specifying properties of MAS have been presented in quite a variety of
scenarios with bounded resources. In this paper, we study a different
formalism, called Priced Resource-Bounded Alternating-time Temporal Logic
(PRBATL), whose main novelty consists in moving the notion of resources from a
syntactic level (part of the formula) to a semantic one (part of the model).
This allows us to track the evolution of the resource availability along the
computations and provides us with a formalisms capable to model a number of
real-world scenarios. Two relevant aspects are the notion of global
availability of the resources on the market, that are shared by the agents, and
the notion of price of resources, depending on their availability. In a
previous work of ours, an initial step towards this new formalism was
introduced, along with an EXPTIME algorithm for the model checking problem. In
this paper we better analyze the features of the proposed formalism, also in
comparison with previous approaches. The main technical contribution is the
proof of the EXPTIME-hardness of the the model checking problem for PRBATL,
based on a reduction from the acceptance problem for Linearly-Bounded
Alternating Turing Machines. In particular, since the problem has multiple
parameters, we show two fixed-parameter reductions.Comment: In Proceedings GandALF 2013, arXiv:1307.416
Reasoning about Knowledge in Linear Logic: Modalities and Complexity
In a recent paper, Jean-Yves Girard commented that ”it has been a long time since philosophy has stopped intereacting with logic”[17]. Actually, it has no
Extended RDF: Computability and Complexity Issues
ERDF stable model semantics is a recently proposed semantics for
ERDF ontologies and a faithful extension of RDFS semantics on RDF graphs.
In this paper, we elaborate on the computability and complexity issues of the
ERDF stable model semantics. Based on the undecidability result of ERDF
stable model semantics, decidability under this semantics cannot be achieved,
unless ERDF ontologies of restricted syntax are considered. Therefore, we
propose a slightly modified semantics for ERDF ontologies, called ERDF #n-
stable model semantics. We show that entailment under this semantics is, in
general, decidable and also extends RDFS entailment. Equivalence statements
between the two semantics are provided. Additionally, we provide algorithms
that compute the ERDF #n-stable models of syntax-restricted and general
ERDF ontologies. Further, we provide complexity results for the ERDF #nstable
model semantics on syntax-restricted and general ERDF ontologies.
Finally, we provide complexity results for the ERDF stable model semantics
on syntax-restricted ERDF ontologies
- …