3,490 research outputs found
Non-simplifying Graph Rewriting Termination
So far, a very large amount of work in Natural Language Processing (NLP) rely
on trees as the core mathematical structure to represent linguistic
informations (e.g. in Chomsky's work). However, some linguistic phenomena do
not cope properly with trees. In a former paper, we showed the benefit of
encoding linguistic structures by graphs and of using graph rewriting rules to
compute on those structures. Justified by some linguistic considerations, graph
rewriting is characterized by two features: first, there is no node creation
along computations and second, there are non-local edge modifications. Under
these hypotheses, we show that uniform termination is undecidable and that
non-uniform termination is decidable. We describe two termination techniques
based on weights and we give complexity bound on the derivation length for
these rewriting system.Comment: In Proceedings TERMGRAPH 2013, arXiv:1302.599
Intensional properties of polygraphs
We present polygraphic programs, a subclass of Albert Burroni's polygraphs,
as a computational model, showing how these objects can be seen as first-order
functional programs. We prove that the model is Turing complete. We use
polygraphic interpretations, a termination proof method introduced by the
second author, to characterize polygraphic programs that compute in polynomial
time. We conclude with a characterization of polynomial time functions and
non-deterministic polynomial time functions.Comment: Proceedings of TERMGRAPH 2007, Electronic Notes in Computer Science
(to appear), 12 pages, minor changes from previous versio
Observation of implicit complexity by non confluence
We propose to consider non confluence with respect to implicit complexity. We
come back to some well known classes of first-order functional program, for
which we have a characterization of their intentional properties, namely the
class of cons-free programs, the class of programs with an interpretation, and
the class of programs with a quasi-interpretation together with a termination
proof by the product path ordering. They all correspond to PTIME. We prove that
adding non confluence to the rules leads to respectively PTIME, NPTIME and
PSPACE. Our thesis is that the separation of the classes is actually a witness
of the intentional properties of the initial classes of programs
Analysis and Diversion of Duqu's Driver
The propagation techniques and the payload of Duqu have been closely studied
over the past year and it has been said that Duqu shared functionalities with
Stuxnet. We focused on the driver used by Duqu during the infection, our
contribution consists in reverse-engineering the driver: we rebuilt its source
code and analyzed the mechanisms it uses to execute the payload while avoiding
detection. Then we diverted the driver into a defensive version capable of
detecting injections in Windows binaries, thus preventing further attacks. We
specifically show how Duqu's modified driver would have detected Duqu.Comment: Malware 2013 - 8th International Conference on Malicious and Unwanted
Software (2013
From environmental microbiology to ecogenomics: Spotting the emerging field of fungal-bacterial interactions
Effect of volatiles versus exudates released by germinating spores of Gigaspora margarita on lateral root formation
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