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Effect-Dependent Transformations for Concurrent Programs [article]

Nick Benton, Martin Hofmann, Vivek Nigam
2015 arXiv   pre-print
Abstract Locations We build on the concept of abstract locations defined by Benton, Hofmann, and Nigam [6] .  ... 
arXiv:1510.02419v1 fatcat:caspmk5ghzbxzcb2z63yuzy37a

Subexponentials in non-commutative linear logic [article]

Max Kanovich, Stepan Kuznetsov, Vivek Nigam, Andre Scedrov
2017 arXiv   pre-print
In the recent years, it has been shown that SELL can also be used to specify linear authorization logics [Nigam, 2012 [Nigam, , 2014 , concurrent constraint programming languages [Nigam et al., 2013  ...  , Olarte et al., 2015 and proof systems [Nigam et al., 2016] .  ... 
arXiv:1709.03607v1 fatcat:ft5zuquzsza25a3csdz6hxxqhe

Abstract Effects and Proof-Relevant Logical Relations [article]

Nick Benton, Martin Hofmann, Vivek Nigam
2012 arXiv   pre-print
We introduce a novel variant of logical relations that maps types not merely to partial equivalence relations on values, as is commonly done, but rather to a proof-relevant generalisation thereof, namely setoids. The objects of a setoid establish that values inhabit semantic types, whilst its morphisms are understood as proofs of semantic equivalence. The transition to proof-relevance solves two well-known problems caused by the use of existential quantification over future worlds in
more » ... orlds in traditional Kripke logical relations: failure of admissibility, and spurious functional dependencies. We illustrate the novel format with two applications: a direct-style validation of Pitts and Stark's equivalences for "new" and a denotational semantics for a region-based effect system that supports type abstraction in the sense that only externally visible effects need to be tracked; non-observable internal modifications, such as the reorganisation of a search tree or lazy initialisation, can count as 'pure' or 'read only'. This 'fictional purity' allows clients of a module soundly to validate more effect-based program equivalences than would be possible with traditional effect systems.
arXiv:1212.5692v1 fatcat:45hejd5x4ndodask5skqem6dti

Symbolic Timed Observational Equivalence [article]

Vivek Nigam, Carolyn Talcott, Abrãao Aires Urquiza
2018 arXiv   pre-print
Intruders can infer properties of a system by measuring the time it takes for the system to respond to some request of a given protocol, that is, by exploiting time side channels. These properties may help intruders distinguish whether a system is a honeypot or concrete system helping him avoid defense mechanisms, or track a user among others violating his privacy. Observational equivalence is the technical machinery used for verifying whether two systems are distinguishable. Moreover,
more » ... Moreover, efficient symbolic methods have been developed for automating the check of observational equivalence of systems. This paper introduces a novel definition of timed observational equivalence which also distinguishes systems according to their time side channels. Moreover, as our definition uses symbolic time constraints, it can be automated by using SMT-solvers.
arXiv:1801.04066v2 fatcat:htwe3vebnjfddpamsskpqbvlvi

Subexponential concurrent constraint programming

Carlos Olarte, Elaine Pimentel, Vivek Nigam
2015 Theoretical Computer Science  
In previous works we have shown that linear logic with subexponentials (SELL), a refinement of linear logic, can be used to specify emergent features of concurrent constraint programming (CCP) languages, such as preferences and spatial, epistemic and temporal modalities. In order to do so, we introduced a number of extensions to SELL, such as subexponential quantifiers for the specification of modalities, and more elaborated subexponential structures for the specification of preferences. These
more » ... preferences. These results provided clear proof theoretic foundations to existing systems. This paper goes in the opposite direction, answering positively the question: can the proof theory of linear logic with subexponentials contribute to the development of new CCP languages? We propose a CCP language with the following powerful features: 1) computational spaces where agents can tell and ask preferences (soft-constraints); 2) systems where spatial and temporal modalities can be combined; 3) shared spaces for communication that can be dynamically established; and 4) systems that can dynamically create nested spaces. In order to provide the proof theoretic foundations for such a language, we propose a unified logical framework (SELLS ) combining the extensions of linear logic with subexponentials mentioned above, and showing that this new framework has interesting proof theoretical properties such as cut-elimination and a sound and complete focused proof system.
doi:10.1016/j.tcs.2015.06.031 fatcat:otxe47mfjnf75i4nov2yn7ifya

A framework for linear authorization logics

Vivek Nigam
2014 Theoretical Computer Science  
Nigam was supported by the CNPq.  ...  For instance, in [39, 37] , Nigam et al. extends the conditions to prove cut-elimination proposed in [29] for linear logic to linear logic with subexponentials.  ...  Nigam in [32] proposed a focused proof system for classical linear logic with subexponentials. Here, we review its intuitionistic version. A similar system also appears in [9] .  ... 
doi:10.1016/j.tcs.2014.02.018 fatcat:22pxpnai5vflfhhq6sv6wmwvbi

Compliance in Real Time Multiset Rewriting Models [article]

Max Kanovich, Tajana Ban Kirigin, Vivek Nigam, Andre Scedrov and Carolyn Talcott
2018 arXiv   pre-print
The notion of compliance in Multiset Rewriting Models (MSR) has been introduced for untimed models and for models with discrete time. In this paper we revisit the notion of compliance and adapt it to fit with additional nondeterminism specific for dense time domains. Existing MSR with dense time are extended with critical configurations and non-critical traces, that is, traces involving no critical configurations. Complexity of related non-critical reachability problem is investigated. Although
more » ... estigated. Although this problem is undecidable in general, we prove that for balanced MSR with dense time the non-critical reachability problem is PSPACE-complete.
arXiv:1811.04826v1 fatcat:5frgkske6nbifpwvi77af4en34

Preface

Valeria de Paiva, Mario Benevides, Vivek Nigam, Elaine Pimentel
2014 Electronical Notes in Theoretical Computer Science  
Valeria de Paiva Mario Benevides Vivek Nigam Elaine Pimentel  ... 
doi:10.1016/j.entcs.2013.12.008 fatcat:z5ikgkekrnhxbiqj5etgxthzde

Soft Subexponentials and Multiplexing [chapter]

Max Kanovich, Stepan Kuznetsov, Vivek Nigam, Andre Scedrov
2020 Lecture Notes in Computer Science  
Vivek Nigam is also partially supported by CNPq grant 303909/2018-8. Table 1 . 1 Lambek Calculus: A non-commutative version of ILL Table 2 . 2 SLLM: Lambek calculus with multiplexing. .Fig. 1.  ...  Vivek Nigam's participation in this project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 830892.  ... 
doi:10.1007/978-3-030-51074-9_29 fatcat:rx3qbmznpzdh7fme4xiv27bqgu

A Framework for Proof Systems

Vivek Nigam, Dale Miller
2010 Journal of automated reasoning  
Meta-logics and type systems based on intuitionistic logic are commonly used for specifying natural deduction proof systems. We shall show here that linear logic can be used as a meta-logic to specify a range of object-level proof systems. In particular, we show that by providing different polarizations within a focused proof system for linear logic, one can account for natural deduction (normal and non-normal), sequent proofs (with and without cut), and tableaux proofs. Armed with just a few,
more » ... d with just a few, simple variations to the linear logic encodings, more proof systems can be accommodated, including proof system using generalized elimination and generalized introduction rules. In general, most of these proof systems are developed for both classical and intuitionistic logics. By using simple results about linear logic, we can also give simple and modular proofs of the soundness and relative completeness of all the proof systems we consider.
doi:10.1007/s10817-010-9182-1 fatcat:6e2wtfstabglncb5zgxqe6ccvy

Model-Based Safety and Security Engineering [article]

Vivek Nigam and Alexander Pretschner and Harald Ruess
2019 arXiv   pre-print
By exploiting the increasing surface attack of systems, cyber-attacks can cause catastrophic events, such as, remotely disable safety mechanisms. This means that in order to avoid hazards, safety and security need to be integrated, exchanging information, such as, key hazards/threats, risk evaluations, mechanisms used. This white paper describes some steps towards this integration by using models. We start by identifying some key technical challenges. Then we demonstrate how models, such as
more » ... models, such as Goal Structured Notation (GSN) for safety and Attack Defense Trees (ADT) for security, can address these challenges. In particular, (1) we demonstrate how to extract in an automated fashion security relevant information from safety assessments by translating GSN-Models into ADTs; (2) We show how security results can impact the confidence of safety assessments; (3) We propose a collaborative development process where safety and security assessments are built by incrementally taking into account safety and security analysis; (4) We describe how to carry out trade-off analysis in an automated fashion, such as identifying when safety and security arguments contradict each other and how to solve such contradictions. We conclude pointing out that these are the first steps towards a wide range of techniques to support Safety and Security Engineering. As a white paper, we avoid being too technical, preferring to illustrate features by using examples and thus being more accessible.
arXiv:1810.04866v2 fatcat:b5szqz755vdj7bfgh4xsluqyyy

Online non-invasive fetal sound analysis

Vivek Nigam, Roland Priemer
2004 2004 IEEE Electro/Information Technology Conference  
A method is presented to non-invasively separate the fetal phonocardiograms (FPCG) of the fetuses in a multiple fetus pregnancy. The method uses a device like a stethoscope. We assume that the phonocardiograms of the fetuses are statistically independent. Results of simulations are included in the paper
doi:10.1109/eit.2004.4569381 fatcat:qut5h4vt7banrdkebasbhoo6dq

Proof-Relevant Logical Relations for Name Generation [article]

Nick Benton, Martin Hofmann, Vivek Nigam
2017 arXiv   pre-print
Pitts and Stark's ν-calculus is a paradigmatic total language for studying the problem of contextual equivalence in higher-order languages with name generation. Models for the ν-calculus that validate basic equivalences concerning names may be constructed using functor categories or nominal sets, with a dynamic allocation monad used to model computations that may allocate fresh names. If recursion is added to the language and one attempts to adapt the models from (nominal) sets to (nominal)
more » ... ts to (nominal) domains, however, the direct-style construction of the allocation monad no longer works. This issue has previously been addressed by using a monad that combines dynamic allocation with continuations, at some cost to abstraction. This paper presents a direct-style model of a ν-calculus-like language with recursion using the novel framework of proof-relevant logical relations, in which logical relations also contain objects (or proofs) demonstrating the equivalence of (the semantic counterparts of) programs. Apart from providing a fresh solution to an old problem, this work provides an accessible setting in which to introduce the use of proof-relevant logical relations, free of the additional complexities associated with their use for more sophisticated languages.
arXiv:1708.05193v1 fatcat:7awf2fmvqbbbllgiblm74amf3m

Bounded memory protocols

Max Kanovich, Tajana Ban Kirigin, Vivek Nigam, Andre Scedrov
2014 Computer languages, systems & structures  
Nigam was partially supported by the Alexander von Humboldt Foundation and CNPq. Kanovich was partially supported by the EPSRC.  ... 
doi:10.1016/j.cl.2014.05.003 fatcat:tsydq6ohhzcnnncl25te5drp4i

Proof-Relevant Logical Relations for Name Generation [chapter]

Nick Benton, Martin Hofmann, Vivek Nigam
2013 Lecture Notes in Computer Science  
Pitts and Stark's ν-calculus is a paradigmatic total language for studying the problem of contextual equivalence in higher-order languages with name generation. Models for the ν-calculus that validate basic equivalences concerning names may be constructed using functor categories or nominal sets, with a dynamic allocation monad used to model computations that may allocate fresh names. If recursion is added to the language and one attempts to adapt the models from (nominal) sets to (nominal)
more » ... ts to (nominal) domains, however, the direct-style construction of the allocation monad no longer works. This issue has previously been addressed by using a monad that combines dynamic allocation with continuations, at some cost to abstraction. This paper presents a direct-style model of a ν-calculus-like language with recursion using the novel framework of proof-relevant logical relations, in which logical relations also contain objects (or proofs) demonstrating the equivalence of (the semantic counterparts of) programs. Apart from providing a fresh solution to an old problem, this work provides an accessible setting in which to introduce the use of proof-relevant logical relations, free of the additional complexities associated with their use for more sophisticated languages.
doi:10.1007/978-3-642-38946-7_6 fatcat:qxyfqkonajhilg4zc3pybwsehm
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