Proof Search Tree and Cut Elimination

2008 ◽  
pp. 521-536
Author(s):  
Grigori Mints
Keyword(s):  
Search Tree ◽  
Cut Elimination ◽  
Proof Search

Cut elimination and complexity bounds for intuitionistic epistemic logic

2020 ◽  
Vol 30 (1) ◽  
pp. 281-294
Author(s):  
Vladimir N Krupski
Keyword(s):  
Epistemic Logic ◽  
Sequent Calculus ◽  
Formal System ◽  
Point Of View ◽  
Cut Elimination ◽  
Polynomial Space ◽  
Complexity Bounds ◽  
Proof Search

Abstract The formal system of intuitionistic epistemic logic (IEL) was proposed by S. Artemov and T. Protopopescu. It provides the formal foundation for the study of knowledge from an intuitionistic point of view based on Brouwer–Heyting–Kolmogorov semantics of intuitionism. We construct a cut-free sequent calculus for IEL and establish that polynomial space is sufficient for the proof search in it. We prove that IEL is PSPACE-complete.

A multi-labelled sequent calculus for Topo-Logic

2020 ◽  
Vol 30 (2) ◽  
pp. 663-696
Author(s):  
Ian Shillito
Keyword(s):  
Structural Properties ◽  
Epistemic Logic ◽  
Search Strategy ◽  
Sequent Calculus ◽  
Search Tree ◽  
Topological Spaces ◽  
Label Technique ◽  
Proof Search ◽  
Labelled Sequent Calculus

Abstract We present a labelled sequent calculus for a trimodal epistemic logic exhibitied in Baltag et al. (2017, Logic, Rationality, and Interaction, pp. 330–346), an extension of the so called ‘Topo-Logic’. To the best of our knowledge, our calculus is the first proof-calculus for this logic. This calculus is obtained via an adaptation of the label technique by internalizing a semantics over topological spaces. This internalization leads to the generation of two kinds of labels in our calculus and the labelling of formulae by pairs of labels. These novelties give tools to provide a simple calculus that is intuitively connected to the semantics. We prove that this calculus enjoys many structural properties such as admissibility of cut, admissibility of contraction and invertibility of its rules. Finally, we exhibit a proof search strategy for our calculus that allows us to prove completeness in a direct way by the extraction of a countermodel from a failure of proof. To define this strategy, we design a tool for controlling the generation of labels in the construction of a search tree, although the termination of this strategy is still open.

Cut-Elimination for Provability Logic by Terminating Proof-Search: Formalised and Deconstructed Using Coq

2021 ◽  
pp. 299-313
Author(s):  
Rajeev Goré ◽  
Revantha Ramanayake ◽  
Ian Shillito
Keyword(s):  
Cut Elimination ◽  
Provability Logic ◽  
Proof Search

Contraction-free sequent calculi for intuitionistic logic

1992 ◽  
Vol 57 (3) ◽  
pp. 795-807 ◽  
Author(s):  
Roy Dyckhoff
Keyword(s):  
Sequent Calculus ◽  
Main Idea ◽  
Simple Algorithm ◽  
Propositional Calculus ◽  
Search Tree ◽  
Sequent Calculi ◽  
Proof Search ◽  
Intuitionistic Propositional Calculus ◽  
Effective Decision ◽  
Subformula Property

Gentzen's sequent calculus LJ, and its variants such as G3 [21], are (as is well known) convenient as a basis for automating proof search for IPC (intuitionistic propositional calculus). But a problem arises: that of detecting loops, arising from the use (in reverse) of the rule ⊃⇒ for implication introduction on the left. We describe below an equivalent calculus, yet another variant on these systems, where the problem no longer arises: this gives a simple but effective decision procedure for IPC.The underlying method can be traced back forty years to Vorob′ev [33], [34]. It has been rediscovered recently by several authors (the present author in August 1990, Hudelmaier [18], [19], Paulson [27], and Lincoln et al. [23]). Since the main idea is not plainly apparent in Vorob′ev's work, and there are mathematical applications [28], it is desirable to have a simple proof. We present such a proof, exploiting the Dershowtiz-Manna theorem [4] on multiset orderings.Consider the task of constructing proofs in Gentzen's sequent calculus LJ of intuitionistic sequents Γ⇒ G, where Γ is a set of assumption formulae and G is a formula (in the language of zero-order logic, using the nullary constant f [absurdity], the unary constant ¬ [negation, with ¬A =defA ⊃ f] and the binary constants &, ∨, and ⊃ [conjunction, disjunction, and implication respectively]). By the Hauptsatz [15], there is an apparently simple algorithm which breaks up the sequent, growing the proof tree until one reaches axioms (of the form Γ⇒ A where A is in Γ), or can make no further progress and must backtrack or even abandon the search. (Gentzen's argument in fact was to use the subformula property derived from the Hauptsatz to limit the size of the search tree. Došen [5] improves on this argument.)

scholarly journals Hypersequent calculi for non-normal modal and deontic logics: countermodels and optimal complexity

2020 ◽  
Author(s):  
Tiziano Dalmonte ◽  
Björn Lellmann ◽  
Nicola Olivetti ◽  
Elaine Pimentel
Keyword(s):  
Search Strategy ◽  
Cut Elimination ◽  
Relational Semantics ◽  
Optimal Complexity ◽  
Proof Search ◽  
Polynomial Size ◽  
Hypersequent Calculi

Abstract We present some hypersequent calculi for all systems of the classical cube and their extensions with axioms ${T}$, ${P}$ and ${D}$ and for every $n \geq 1$, rule ${RD}_n^+$. The calculi are internal as they only employ the language of the logic, plus additional structural connectives. We show that the calculi are complete with respect to the corresponding axiomatization by a syntactic proof of cut elimination. Then, we define a terminating proof search strategy in the hypersequent calculi and show that it is optimal for coNP-complete logics. Moreover, we show that from every failed proof of a formula or hypersequent it is possible to directly extract a countermodel of it in the bi-neighbourhood semantics of polynomial size for coNP logics, and for regular logics also in the relational semantics. We finish the paper by giving a translation between hypersequent rule applications and derivations in a labelled system for the classical cube.

scholarly journals Focused Proof-search in the Logic of Bunched Implications

2021 ◽  
pp. 247-267
Author(s):  
Alexander Gheorghiu ◽  
Sonia Marin
Keyword(s):  
Data Structure ◽  
Proof Theory ◽  
Sequent Calculus ◽  
Operational Semantics ◽  
Search Space ◽  
Difficult Problem ◽  
Cut Elimination ◽  
Proof Search ◽  
Nested Sequents

AbstractThe logic of Bunched Implications (BI) freely combines additive and multiplicative connectives, including implications; however, despite its well-studied proof theory, proof-search in BI has always been a difficult problem. The focusing principle is a restriction of the proof-search space that can capture various goal-directed proof-search procedures. In this paper we show that focused proof-search is complete for BI by first reformulating the traditional bunched sequent calculus using the simpler data-structure of nested sequents, following with a polarised and focused variant that we show is sound and complete via a cut-elimination argument. This establishes an operational semantics for focused proof-search in the logic of Bunched Implications.

Requirements Prioritization Techniques for Global Software Engineering

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Samina Saghir ◽  
Tasleem Mustafa
Keyword(s):  
Software Engineering ◽  
Requirements Engineering ◽  
Search Tree ◽  
Software Requirements ◽  
Binary Search Tree ◽  
Time Zone ◽  
Analytic Hierarchy ◽  
Requirements Prioritization ◽  
Global Software Engineering ◽  
Hierarchy Process

<p>Increase in globalization of the industry of software requires an exploration of requirements engineering (RE) in software development institutes at multiple locations. Requirements engineering task is very complicated when it is performed at single site, but it becomes too much complex when stakeholder groups define well-designed requirements under language, time zone and cultural limits. Requirements prioritization (RP) is considered as an imperative part of software requirements engineering in which requirements are ranked to develop best-quality software. In this research, a comparative study of the requirements prioritization techniques was done to overcome the challenges initiated by the corporal distribution of stakeholders within the organization at multiple locations. The objective of this study was to make a comparison between five techniques for prioritizing software requirements and to discuss the results for global software engineering. The selected techniques were Analytic Hierarchy Process (AHP), Cumulative Voting (CV), Value Oriented Prioritization (VOP), Binary Search Tree (BST), and Numerical Assignment Technique (NAT). At the end of the research a framework for Global Software Engineering (GSE) was proposed to prioritize the requirements for stakeholders at distributed locations.<strong></strong></p>

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