46,990 research outputs found
Save up to 99% of your time in mapping validation
Identifying semantic correspondences between different vocabularies has been recognized as a fundamental step towards achieving interoperability. Several manual and automatic techniques have been recently proposed. Fully manual approaches are very precise, but extremely costly. Conversely, automatic approaches tend to fail when domain specific background knowledge is needed. Consequently, they typically require a manual validation step. Yet, when the number of computed correspondences is very large, the validation phase can be very expensive. In order to reduce the problems above, we propose to compute the minimal set of correspondences, that we call the minimal mapping, which are sufficient to compute all the other ones. We show that by concentrating on such correspondences we can save up to 99% of the manual checks required for validation
Tree Contractions and Evolutionary Trees
An evolutionary tree is a rooted tree where each internal vertex has at least
two children and where the leaves are labeled with distinct symbols
representing species. Evolutionary trees are useful for modeling the
evolutionary history of species. An agreement subtree of two evolutionary trees
is an evolutionary tree which is also a topological subtree of the two given
trees. We give an algorithm to determine the largest possible number of leaves
in any agreement subtree of two trees T_1 and T_2 with n leaves each. If the
maximum degree d of these trees is bounded by a constant, the time complexity
is O(n log^2(n)) and is within a log(n) factor of optimal. For general d, this
algorithm runs in O(n d^2 log(d) log^2(n)) time or alternatively in O(n d
sqrt(d) log^3(n)) time
Simultaneous Finite Automata: An Efficient Data-Parallel Model for Regular Expression Matching
Automata play important roles in wide area of computing and the growth of
multicores calls for their efficient parallel implementation. Though it is
known in theory that we can perform the computation of a finite automaton in
parallel by simulating transitions, its implementation has a large overhead due
to the simulation. In this paper we propose a new automaton called simultaneous
finite automaton (SFA) for efficient parallel computation of an automaton. The
key idea is to extend an automaton so that it involves the simulation of
transitions. Since an SFA itself has a good property of parallelism, we can
develop easily a parallel implementation without overheads. We have implemented
a regular expression matcher based on SFA, and it has achieved over 10-times
speedups on an environment with dual hexa-core CPUs in a typical case.Comment: This paper has been accepted at the following conference: 2013
International Conference on Parallel Processing (ICPP- 2013), October 1-4,
2013 Ecole Normale Suprieure de Lyon, Lyon, Franc
On multiplicity of mappings between surfaces
Let M and N be two closed (not necessarily orientable) surfaces, and f a
continuous map from M to N. By definition, the minimal multiplicity MMR[f] of
the map f denotes the minimal integer k having the following property: f can be
deformed into a map g such that the number |g^{-1}(c)| of preimages of any
point c in N under g is at most k. We calculate MMR[f] for any map of
positive absolute degree A(f). The answer is formulated in terms of A(f),
[pi_1(N):f_#(pi_1(M))], and the Euler characteristics of M and N. For a map f
with A(f)=0, we prove the inequalities 2 <= MMR[f] <= 4.Comment: This is the version published by Geometry & Topology Monographs on 29
April 200
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