112 research outputs found
A logic road from special relativity to general relativity
We present a streamlined axiom system of special relativity in first-order
logic. From this axiom system we "derive" an axiom system of general relativity
in two natural steps. We will also see how the axioms of special relativity
transform into those of general relativity. This way we hope to make general
relativity more accessible for the non-specialist
Enhancing Symbolic Execution of Heap-based Programs with Separation Logic for Test Input Generation
Symbolic execution is a well established method for test input generation.
Despite of having achieved tremendous success over numerical domains, existing
symbolic execution techniques for heap-based programs are limited due to the
lack of a succinct and precise description for symbolic values over unbounded
heaps. In this work, we present a new symbolic execution method for heap-based
programs based on separation logic. The essence of our proposal is
context-sensitive lazy initialization, a novel approach for efficient test
input generation. Our approach differs from existing approaches in two ways.
Firstly, our approach is based on separation logic, which allows us to
precisely capture preconditions of heap-based programs so that we avoid
generating invalid test inputs. Secondly, we generate only fully initialized
test inputs, which are more useful in practice compared to those partially
initialized test inputs generated by the state-of-the-art tools. We have
implemented our approach as a tool, called Java StarFinder, and evaluated it on
a set of programs with complex heap inputs. The results show that our approach
significantly reduces the number of invalid test inputs and improves the test
coverage
Changing a semantics: opportunism or courage?
The generalized models for higher-order logics introduced by Leon Henkin, and
their multiple offspring over the years, have become a standard tool in many
areas of logic. Even so, discussion has persisted about their technical status,
and perhaps even their conceptual legitimacy. This paper gives a systematic
view of generalized model techniques, discusses what they mean in mathematical
and philosophical terms, and presents a few technical themes and results about
their role in algebraic representation, calibrating provability, lowering
complexity, understanding fixed-point logics, and achieving set-theoretic
absoluteness. We also show how thinking about Henkin's approach to semantics of
logical systems in this generality can yield new results, dispelling the
impression of adhocness. This paper is dedicated to Leon Henkin, a deep
logician who has changed the way we all work, while also being an always open,
modest, and encouraging colleague and friend.Comment: 27 pages. To appear in: The life and work of Leon Henkin: Essays on
his contributions (Studies in Universal Logic) eds: Manzano, M., Sain, I. and
Alonso, E., 201
Technologies of Attribution: Characterizing the Citizen-Consumer in Surveillance Performance
Many accounts of surveillance and its subjective effects tend to focus on privacy. Along with this focus comes the assumption that surveillanceâs objects are simply facts and attributes, straightforwardly âminedâ (or stolen) from peopleâs private lives. Yet, the habits and propensities ascribed to individuals through surveillance apparatuses are complex, relational phenomena: co-produced, selected and interpreted with interest by various actors. This essay begins to develop a critical language for surveillance as a form of characterization, by analysing SWAMP's McService (2003), Hasan Elahiâs Tracking Transience (2005â) and Erica Scourtiâs Life in AdWords (2012â2013). Following Sara Ahmed, I theorize characterization as a âtechnology of attributionâ that attaches such interpretations of character to people within surveillant scenarios. Drawing from literary studies as well as recent work on the surveillance economy, I analyse the forms of attribution made possible within surveillant scenarios. Within SWAMP, Elahi and Scourti's works, which span a decade between 9/11 and the Snowden revelations, one can trace an evolution of structures through which such attributions manifest: from self as threat, to self as set, to self as product
Introducing LoCo, a Logic for Configuration Problems
In this paper we present the core of LoCo, a logic-based high-level
representation language for expressing configuration problems. LoCo shall allow
to model these problems in an intuitive and declarative way, the dynamic
aspects of configuration notwithstanding. Our logic enforces that
configurations contain only finitely many components and reasoning can be
reduced to the task of model construction.Comment: In Proceedings LoCoCo 2011, arXiv:1108.609
Removing Algebraic Data Types from Constrained Horn Clauses Using Difference Predicates
We address the problem of proving the satisfiability of Constrained Horn
Clauses (CHCs) with Algebraic Data Types (ADTs), such as lists and trees. We
propose a new technique for transforming CHCs with ADTs into CHCs where
predicates are defined over basic types, such as integers and booleans, only.
Thus, our technique avoids the explicit use of inductive proof rules during
satisfiability proofs. The main extension over previous techniques for ADT
removal is a new transformation rule, called differential replacement, which
allows us to introduce auxiliary predicates corresponding to the lemmas that
are often needed when making inductive proofs. We present an algorithm that
uses the new rule, together with the traditional folding/unfolding
transformation rules, for the automatic removal of ADTs. We prove that if the
set of the transformed clauses is satisfiable, then so is the set of the
original clauses. By an experimental evaluation, we show that the use of the
differential replacement rule significantly improves the effectiveness of ADT
removal, and we show that our transformation-based approach is competitive with
respect to a well-established technique that extends the CVC4 solver with
induction.Comment: 10th International Joint Conference on Automated Reasoning (IJCAR
2020) - version with appendix; added DOI of the final authenticated Springer
publication; minor correction
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