593 research outputs found
Two-Sided Derivatives for Regular Expressions and for Hairpin Expressions
The aim of this paper is to design the polynomial construction of a finite
recognizer for hairpin completions of regular languages. This is achieved by
considering completions as new expression operators and by applying derivation
techniques to the associated extended expressions called hairpin expressions.
More precisely, we extend partial derivation of regular expressions to
two-sided partial derivation of hairpin expressions and we show how to deduce a
recognizer for a hairpin expression from its two-sided derived term automaton,
providing an alternative proof of the fact that hairpin completions of regular
languages are linear context-free.Comment: 28 page
The KB paradigm and its application to interactive configuration
The knowledge base paradigm aims to express domain knowledge in a rich formal
language, and to use this domain knowledge as a knowledge base to solve various
problems and tasks that arise in the domain by applying multiple forms of
inference. As such, the paradigm applies a strict separation of concerns
between information and problem solving. In this paper, we analyze the
principles and feasibility of the knowledge base paradigm in the context of an
important class of applications: interactive configuration problems. In
interactive configuration problems, a configuration of interrelated objects
under constraints is searched, where the system assists the user in reaching an
intended configuration. It is widely recognized in industry that good software
solutions for these problems are very difficult to develop. We investigate such
problems from the perspective of the KB paradigm. We show that multiple
functionalities in this domain can be achieved by applying different forms of
logical inferences on a formal specification of the configuration domain. We
report on a proof of concept of this approach in a real-life application with a
banking company. To appear in Theory and Practice of Logic Programming (TPLP).Comment: To appear in Theory and Practice of Logic Programming (TPLP
Certification of Compiler Optimizations using Kleene Algebra with Tests
We use Kleene algebra with tests to verify a wide assortment of common compiler optimizations, including dead code elimination, common subexpression elimination, copy propagation, loop hoisting, induction variable elimination, instruction scheduling, algebraic simplification, loop unrolling, elimination of redundant instructions, array bounds check elimination, and introduction of sentinels. In each of these cases, we give a formal equational proof of the correctness of the optimizing transformation
A Selective PMCA Inhibitor Does Not Prolong the Electroolfactogram in Mouse
Within the cilia of vertebrate olfactory receptor neurons, Ca(2+) accumulates during odor transduction. Termination of the odor response requires removal of this Ca(2+), and prior evidence suggests that both Na(+)/Ca(2+) exchange and plasma membrane Ca(2+)-ATPase (PMCA) contribute to this removal.In intact mouse olfactory epithelium, we measured the time course of termination of the odor-induced field potential. Replacement of mucosal Na(+) with Li(+), which reduces the ability of Na(+)/Ca(2+) exchange to expel Ca(2+), prolonged the termination as expected. However, treating the epithelium with the specific PMCA inhibitor caloxin 1b1 caused no significant increase in the time course of response termination.Under these experimental conditions, PMCA does not contribute detectably to the termination of the odor response
Limits of Calcium Clearance by Plasma Membrane Calcium ATPase in Olfactory Cilia
BACKGROUND: In any fine sensory organelle, a small influx of Ca(2+) can quickly elevate cytoplasmic Ca(2+). Mechanisms must exist to clear the ciliary Ca(2+) before it reaches toxic levels. One such organelle has been well studied: the vertebrate olfactory cilium. Recent studies have suggested that clearance from the olfactory cilium is mediated in part by plasma membrane Ca(2+)-ATPase (PMCA). PRINCIPAL FINDINGS: In the present study, electrophysiological assays were devised to monitor cytoplasmic free Ca(2+) in single frog olfactory cilia. Ca(2+) was allowed to enter isolated cilia, either through the detached end or through membrane channels. Intraciliary Ca(2+) was monitored via the activity of ciliary Ca(2+)-gated Cl(-) channels, which are sensitive to free Ca(2+) from about 2 to 10 microM. No significant effect of MgATP on intraciliary free Ca(2+) could be found. Carboxyeosin, which has been used to inhibit PMCA, was found to substantially increase a ciliary transduction current activated by cyclic AMP. This increase was ATP-independent. CONCLUSIONS: Alternative explanations are suggested for two previous experiments taken to support a role for PMCA in ciliary Ca(2+) clearance. It is concluded that PMCA in the cilium plays a very limited role in clearing the micromolar levels of intraciliary Ca(2+) produced during the odor response
Quantum measurement occurrence is undecidable
In this work, we show that very natural, apparently simple problems in
quantum measurement theory can be undecidable even if their classical analogues
are decidable. Undecidability hence appears as a genuine quantum property here.
Formally, an undecidable problem is a decision problem for which one cannot
construct a single algorithm that will always provide a correct answer in
finite time. The problem we consider is to determine whether sequentially used
identical Stern-Gerlach-type measurement devices, giving rise to a tree of
possible outcomes, have outcomes that never occur. Finally, we point out
implications for measurement-based quantum computing and studies of quantum
many-body models and suggest that a plethora of problems may indeed be
undecidable.Comment: 4+ pages, 1 figure, added a proof that the QMOP is still undecidable
for exponentially small but nonzero probabilit
Health-related quality of life among adult HIV positive patients : assessing comprehensive themes and interrelated associations
Acknowledgements We would like to thank all HIV doctors, HIV nurses and clinical nurse specialists for their help with the inclusion of patients in the study. We are further grateful to all patients who filled out the questionnaires.Peer reviewedPublisher PD
Biogenesis of mitochondrial porin
We review here the present knowledge about the pathway of import and assembly of porin into mitochondria and compare it to those of other mitochondrial proteins. Porin, like all outer mitochondrial membrane proteins studied so far is made as a precursor without a cleavble lsquosignalrsquo sequence; thus targeting information must reside in the mature sequence. At least part of this information appears to be located at the amino-terminal end of the molecule. Transport into mitochondria can occur post-translationally. In a first step, the porin precursor is specifically recognized on the mitochondrial surface by a protease sensitive receptor. In a second step, porin precursor inserts partially into the outer membrane. This step is mediated by a component of the import machinery common to the import pathways of precursor proteins destined for other mitochondrial subcompartments. Finally, porin is assembled to produce the functional oligomeric form of an integral membrane protein wich is characterized by its extreme protease resistance
Causality - Complexity - Consistency: Can Space-Time Be Based on Logic and Computation?
The difficulty of explaining non-local correlations in a fixed causal
structure sheds new light on the old debate on whether space and time are to be
seen as fundamental. Refraining from assuming space-time as given a priori has
a number of consequences. First, the usual definitions of randomness depend on
a causal structure and turn meaningless. So motivated, we propose an intrinsic,
physically motivated measure for the randomness of a string of bits: its length
minus its normalized work value, a quantity we closely relate to its Kolmogorov
complexity (the length of the shortest program making a universal Turing
machine output this string). We test this alternative concept of randomness for
the example of non-local correlations, and we end up with a reasoning that
leads to similar conclusions as in, but is conceptually more direct than, the
probabilistic view since only the outcomes of measurements that can actually
all be carried out together are put into relation to each other. In the same
context-free spirit, we connect the logical reversibility of an evolution to
the second law of thermodynamics and the arrow of time. Refining this, we end
up with a speculation on the emergence of a space-time structure on bit strings
in terms of data-compressibility relations. Finally, we show that logical
consistency, by which we replace the abandoned causality, it strictly weaker a
constraint than the latter in the multi-party case.Comment: 17 pages, 16 figures, small correction
Chatbot Theory: A naïve and elementary theory for dialogue management
Due to the increasing interested and use of chatbot, its properties and operation possibilities shall be proper realized matching both safety and security issues as well as present the several uses and compositions that this technology supports. This paper focus is on dialogue management since it is considered the core of a chatbot. The dialogue manager is responsible to, more than to transform an input sentence into an output one, hold the illusion of a human conversation. In this sense, it is presented an inceptive theoretical framework through a formal way for chatbots that can be used as a reference to explore, compose, build and discuss chatbots. The discussion is performed mostly on ELIZA since, due to its historical records, it can be considered an important reference chatbot, nevertheless, the proposed theory is compatible with the most recent technologies such those using machine and deep learning. The paper then presents some sketchy instances in order to explore the support provided by the theory.This paper has been supported by COMPETE: POCI-01-0145-FEDER-0070 43 and FCT – Fundação
para a Ciência e Tecnologia - Project UID/CEC/ 00319/2013
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