78,725 research outputs found
Adaptive Representations for Tracking Breaking News on Twitter
Twitter is often the most up-to-date source for finding and tracking breaking
news stories. Therefore, there is considerable interest in developing filters
for tweet streams in order to track and summarize stories. This is a
non-trivial text analytics task as tweets are short, and standard retrieval
methods often fail as stories evolve over time. In this paper we examine the
effectiveness of adaptive mechanisms for tracking and summarizing breaking news
stories. We evaluate the effectiveness of these mechanisms on a number of
recent news events for which manually curated timelines are available.
Assessments based on ROUGE metrics indicate that an adaptive approaches are
best suited for tracking evolving stories on Twitter.Comment: 8 Pag
Simulation of Rapidly-Exploring Random Trees in Membrane Computing with P-Lingua and Automatic Programming
Methods based on Rapidly-exploring Random Trees (RRTs) have been
widely used in robotics to solve motion planning problems. On the other hand, in the
membrane computing framework, models based on Enzymatic Numerical P systems
(ENPS) have been applied to robot controllers, but today there is a lack of planning
algorithms based on membrane computing for robotics. With this motivation, we
provide a variant of ENPS called Random Enzymatic Numerical P systems with
Proteins and Shared Memory (RENPSM) addressed to implement RRT algorithms
and we illustrate it by simulating the bidirectional RRT algorithm. This paper is an
extension of [21]a. The software presented in [21] was an ad-hoc simulator, i.e, a tool
for simulating computations of one and only one model that has been hard-coded.
The main contribution of this paper with respect to [21] is the introduction of a novel
solution for membrane computing simulators based on automatic programming. First,
we have extended the P-Lingua syntax âa language to define membrane computing
modelsâ to write RENPSM models. Second, we have implemented a new parser based
on Flex and Bison to read RENPSM models and produce source code in C language
for multicore processors with OpenMP. Finally, additional experiments are presented.Ministerio de EconomĂa, Industria y Competitividad TIN2017-89842-
Tailored Source Code Transformations to Synthesize Computationally Diverse Program Variants
The predictability of program execution provides attackers a rich source of
knowledge who can exploit it to spy or remotely control the program. Moving
target defense addresses this issue by constantly switching between many
diverse variants of a program, which reduces the certainty that an attacker can
have about the program execution. The effectiveness of this approach relies on
the availability of a large number of software variants that exhibit different
executions. However, current approaches rely on the natural diversity provided
by off-the-shelf components, which is very limited. In this paper, we explore
the automatic synthesis of large sets of program variants, called sosies.
Sosies provide the same expected functionality as the original program, while
exhibiting different executions. They are said to be computationally diverse.
This work addresses two objectives: comparing different transformations for
increasing the likelihood of sosie synthesis (densifying the search space for
sosies); demonstrating computation diversity in synthesized sosies. We
synthesized 30184 sosies in total, for 9 large, real-world, open source
applications. For all these programs we identified one type of program analysis
that systematically increases the density of sosies; we measured computation
diversity for sosies of 3 programs and found diversity in method calls or data
in more than 40% of sosies. This is a step towards controlled massive
unpredictability of software
Acceptability with general orderings
We present a new approach to termination analysis of logic programs. The
essence of the approach is that we make use of general orderings (instead of
level mappings), like it is done in transformational approaches to logic
program termination analysis, but we apply these orderings directly to the
logic program and not to the term-rewrite system obtained through some
transformation. We define some variants of acceptability, based on general
orderings, and show how they are equivalent to LD-termination. We develop a
demand driven, constraint-based approach to verify these
acceptability-variants.
The advantage of the approach over standard acceptability is that in some
cases, where complex level mappings are needed, fairly simple orderings may be
easily generated. The advantage over transformational approaches is that it
avoids the transformation step all together.
{\bf Keywords:} termination analysis, acceptability, orderings.Comment: To appear in "Computational Logic: From Logic Programming into the
Future
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