196,173 research outputs found
Value Types in Eiffel
Identifies a number of problems with Eiffel's expanded types in modelling value types, and proposes a backward compatible syntactic extension, and a modified semantics. The latter is also shown to be (effectively) backward compatible, in the sense that existing programs would run unaffected if compilers implemented the new semantics. The benefits of the approach are discussed, including an elegant approach to rebuilding data structure libraries
Semantics and Security Issues in JavaScript
There is a plethora of research articles describing the deep semantics of
JavaScript. Nevertheless, such articles are often difficult to grasp for
readers not familiar with formal semantics. In this report, we propose a digest
of the semantics of JavaScript centered around security concerns. This document
proposes an overview of the JavaScript language and the misleading semantic
points in its design. The first part of the document describes the main
characteristics of the language itself. The second part presents how those
characteristics can lead to problems. It finishes by showing some coding
patterns to avoid certain traps and presents some ECMAScript 5 new features.Comment: Deliverable Resilience FUI 12: 7.3.2.1 Failles de s\'ecurit\'e en
JavaScript / JavaScript security issue
Displayed Categories
We introduce and develop the notion of *displayed categories*.
A displayed category over a category C is equivalent to "a category D and
functor F : D --> C", but instead of having a single collection of "objects of
D" with a map to the objects of C, the objects are given as a family indexed by
objects of C, and similarly for the morphisms. This encapsulates a common way
of building categories in practice, by starting with an existing category and
adding extra data/properties to the objects and morphisms.
The interest of this seemingly trivial reformulation is that various
properties of functors are more naturally defined as properties of the
corresponding displayed categories. Grothendieck fibrations, for example, when
defined as certain functors, use equality on objects in their definition. When
defined instead as certain displayed categories, no reference to equality on
objects is required. Moreover, almost all examples of fibrations in nature are,
in fact, categories whose standard construction can be seen as going via
displayed categories.
We therefore propose displayed categories as a basis for the development of
fibrations in the type-theoretic setting, and similarly for various other
notions whose classical definitions involve equality on objects.
Besides giving a conceptual clarification of such issues, displayed
categories also provide a powerful tool in computer formalisation, unifying and
abstracting common constructions and proof techniques of category theory, and
enabling modular reasoning about categories of multi-component structures. As
such, most of the material of this article has been formalised in Coq over the
UniMath library, with the aim of providing a practical library for use in
further developments.Comment: v3: Revised and slightly expanded for publication in LMCS. Theorem
numbering change
Solving the TTC 2011 Model Migration Case with UML-RSDS
In this paper we apply the UML-RSDS notation and tools to the GMF model
migration case study and explain how to use the UML-RSDS tools.Comment: In Proceedings TTC 2011, arXiv:1111.440
Compensation methods to support cooperative applications: A case study in automated verification of schema requirements for an advanced transaction model
Compensation plays an important role in advanced transaction models, cooperative work and workflow systems. A schema designer is typically required to supply for each transaction another transaction to semantically undo the effects of . Little attention has been paid to the verification of the desirable properties of such operations, however. This paper demonstrates the use of a higher-order logic theorem prover for verifying that compensating transactions return a database to its original state. It is shown how an OODB schema is translated to the language of the theorem prover so that proofs can be performed on the compensating transactions
The Emergence of Symbolic Algebra as a Shift in Predominant Models
Historians of science find it difficult to pinpoint to an exact period in which symbolic algebra came into existence. This can be explained partly because the historical process leading to this breakthrough in mathematics has been a complex and diffuse one. On the other hand, it might also be the case that in the early twentieth century, historians of mathematics over emphasized the achievements in algebraic procedures and underestimated the conceptual changes leading to symbolic algebra. This paper attempts to provide a more precise setting for the historical context in which this decisive step to symbolic reasoning took place. For that purpose we will consider algebraic problem solving as model-based reasoning and symbolic representation as a model. This allows us to characterize the emergence of symbolic algebra as a shift from a geometrical to a symbolic mode of representation. The use of the symbolic as a model will be situated in the context of mercantilism where merchant activity of exchange has led to reciprocal relations between money and wealth
Combinatorial algebra for second-quantized Quantum Theory
We describe an algebra G of diagrams that faithfully gives a diagrammatic representation of the structures of both the Heisenberg–Weyl algebra H – the associative algebra of the creation and annihilation operators of quantum mechanics – and U(LH), the enveloping algebra of the Heisenberg Lie algebra LH. We show explicitly how G may be endowed with the structure of a Hopf algebra, which is also mirrored in the structure of U(LH). While both H and U(LH) are images of G, the algebra G has a richer structure and therefore embodies a finer combinatorial realization of the creation–annihilation system, of which it provides a concrete model
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