2,883 research outputs found
A B+-tree index for the know-it-all database framework
An efficient implementation of search trees is crucial for any database systems. The B+-tree is one of the most widely and studied data structures and provides an efficient index structure for databases. The Index subframework is a component of the Know-It-All database framework. It covers tree-based indexes such as B+-tree, R-tree, X-tree and SS-tree, including sequential queries, exact match queries, range queries, approximate queries, and similarity queries. Our B+-tree implementation is a proof-of-concept for the Index subframework. Our B+-tree index is designed to be a container by following the STL style in C++ and implemented by using design patterns and generic programming techniques. Therefore, the B+-tree index can adapt to different key types, data types, different queries, and different database application domains, and be easy and convenient for developers to reuse
On the Relation of Interaction Semantics to Continuations and Defunctionalization
In game semantics and related approaches to programming language semantics,
programs are modelled by interaction dialogues. Such models have recently been
used in the design of new compilation methods, e.g. for hardware synthesis or
for programming with sublinear space. This paper relates such semantically
motivated non-standard compilation methods to more standard techniques in the
compilation of functional programming languages, namely continuation passing
and defunctionalization. We first show for the linear {\lambda}-calculus that
interpretation in a model of computation by interaction can be described as a
call-by-name CPS-translation followed by a defunctionalization procedure that
takes into account control-flow information. We then establish a relation
between these two compilation methods for the simply-typed {\lambda}-calculus
and end by considering recursion
A Metric for Linear Temporal Logic
We propose a measure and a metric on the sets of infinite traces generated by
a set of atomic propositions. To compute these quantities, we first map
properties to subsets of the real numbers and then take the Lebesgue measure of
the resulting sets. We analyze how this measure is computed for Linear Temporal
Logic (LTL) formulas. An implementation for computing the measure of bounded
LTL properties is provided and explained. This implementation leverages SAT
model counting and effects independence checks on subexpressions to compute the
measure and metric compositionally
A Tensor Library for Scientific Computing
The majority of physical phenomena and their computational simulations are described mathematically in terms of tensors and their different algebraic operations. Possibly the most used tensors are the ones of rank 1 and 2, which correspond to the algebraic concepts of vectors and matrices, respectively. Nevertheless, higher rank tensors (specially 3 and 4) appear at all times in different branches of physics and in numerical methods. One of the major drawbacks of high
performance computing is that the code necessary to perform such tensor operations looks different and it is several lines longer than the corresponding one-line mathematical representation. Here we present a C++ tensor library, called LTensor, that we have developed using modern concepts of
object oriented design and expression templates. As it will be shown, the LTensor library is able to mimic the classical indicial notation and follows Einstein convention about indices. Furthermore, it has other additional features than distinguish it from other libraries based on similar concepts: dynamic dimension size, arbitrary contraction order, customizable storage, inherited class structure, arbitrary looping positions on indicial notations, etc.Fil: Limache, Alejandro Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rojas Fredini, Pablo Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin
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