3,342 research outputs found
PyZX: Large Scale Automated Diagrammatic Reasoning
The ZX-calculus is a graphical language for reasoning about ZX-diagrams, a
type of tensor networks that can represent arbitrary linear maps between
qubits. Using the ZX-calculus, we can intuitively reason about quantum theory,
and optimise and validate quantum circuits. In this paper we introduce PyZX, an
open source library for automated reasoning with large ZX-diagrams. We give a
brief introduction to the ZX-calculus, then show how PyZX implements methods
for circuit optimisation, equality validation, and visualisation and how it can
be used in tandem with other software. We end with a set of challenges that
when solved would enhance the utility of automated diagrammatic reasoning.Comment: In Proceedings QPL 2019, arXiv:2004.1475
Behavioral types in programming languages
A recent trend in programming language research is to use behav- ioral type theory to ensure various correctness properties of large- scale, communication-intensive systems. Behavioral types encompass concepts such as interfaces, communication protocols, contracts, and choreography. The successful application of behavioral types requires a solid understanding of several practical aspects, from their represen- tation in a concrete programming language, to their integration with other programming constructs such as methods and functions, to de- sign and monitoring methodologies that take behaviors into account. This survey provides an overview of the state of the art of these aspects, which we summarize as the pragmatics of behavioral types
Refining SCJ Mission Specifications into Parallel Handler Designs
Safety-Critical Java (SCJ) is a recent technology that restricts the
execution and memory model of Java in such a way that applications can be
statically analysed and certified for their real-time properties and safe use
of memory. Our interest is in the development of comprehensive and sound
techniques for the formal specification, refinement, design, and implementation
of SCJ programs, using a correct-by-construction approach. As part of this
work, we present here an account of laws and patterns that are of general use
for the refinement of SCJ mission specifications into designs of parallel
handlers used in the SCJ programming paradigm. Our notation is a combination of
languages from the Circus family, supporting state-rich reactive models with
the addition of class objects and real-time properties. Our work is a first
step to elicit laws of programming for SCJ and fits into a refinement strategy
that we have developed previously to derive SCJ programs.Comment: In Proceedings Refine 2013, arXiv:1305.563
Combining behavioural types with security analysis
Today's software systems are highly distributed and interconnected, and they
increasingly rely on communication to achieve their goals; due to their
societal importance, security and trustworthiness are crucial aspects for the
correctness of these systems. Behavioural types, which extend data types by
describing also the structured behaviour of programs, are a widely studied
approach to the enforcement of correctness properties in communicating systems.
This paper offers a unified overview of proposals based on behavioural types
which are aimed at the analysis of security properties
Trace Equivalence Decision: Negative Tests and Non-determinism
We consider security properties of cryptographic protocols that can be modeled using the notion of trace equivalence. The notion of equivalence is crucial when specifying privacy-type properties, like anonymity, vote-privacy, and unlinkability.
In this paper, we give a calculus that is close to the applied pi calculus and that allows one to capture most existing protocols that rely on classical cryptographic primitives. First, we propose a symbolic semantics for our calculus relying on constraint systems to represent infinite sets of possible traces, and we reduce the decidability of trace equivalence to deciding a notion of symbolic equivalence between sets of constraint systems. Second, we develop an algorithm allowing us to decide whether two sets of constraint systems are in symbolic equivalence or not. Altogether, this yields the first decidability result of trace equivalence for a general class of processes that may involve else branches and/or private channels (for a bounded number of sessions)
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