463 research outputs found
Deterministic stack automata and the quotient operator
AbstractA stack automaton is a pushdown automaton with the added privilege of scanning the contents of its pushdown tape without erasing. In this paper, the deterministic stack automaton with a one-way input (dsa) is considered.It is shown that if L is a language accepted by a dsa and R is a regular set, then L/R={w| for some x in R, wx is in L}, is accepted by a dsa. As a corollary, end markers are not needed on the input of the dsa. It is also shown that if L is accepted by a dsa, then Max(L)={w|w in L and for no x is wx is wx in L} is accepted by a dsa
Subalgebras of FA-presentable algebras
Automatic presentations, also called FA-presentations, were introduced to
extend finite model theory to infinite structures whilst retaining the
solubility of fundamental decision problems. This paper studies FA-presentable
algebras. First, an example is given to show that the class of finitely
generated FA-presentable algebras is not closed under forming finitely
generated subalgebras, even within the class of algebras with only unary
operations. However, it is proven that a finitely generated subalgebra of an
FA-presentable algebra with a single unary operation is itself FA-presentable.
Furthermore, it is proven that the class of unary FA-presentable algebras is
closed under forming finitely generated subalgebras, and that the membership
problem for such subalgebras is decidable.Comment: 19 pages, 6 figure
Time and tape complexity of pushdown automaton languages
An algorithm is presented which will determine whether any string w in Σ*, of length n, is contained in a language L ⊆ Σ* defined by a two-way nondeterministic pushdown automation. This algorithm requires time n3 when implemented on a random access computer. It requires n4 time and n2 tape when implemented on a multitape Turing machine.If the pushdown automaton is deterministic, the algorithm requires n2 time on a random access computer and n2 log n time on a multitape Turing machine
Building the Minimal Automaton of A*X in Linear Time, When X Is of Bounded Cardinality
International audienceWe present an algorithm for constructing the minimal automaton recognizing A∗X, where the pattern X is a set of m (that is a fixed integer) non-empty words over a finite alphabet A whose sum of lengths is n. This algorithm, inspired by Brzozowski's minimization algorithm, uses sparse lists to achieve a linear time complexity with respect to n
Monotone Grid Drawings of Planar Graphs
A monotone drawing of a planar graph is a planar straight-line drawing of
where a monotone path exists between every pair of vertices of in some
direction. Recently monotone drawings of planar graphs have been proposed as a
new standard for visualizing graphs. A monotone drawing of a planar graph is a
monotone grid drawing if every vertex in the drawing is drawn on a grid point.
In this paper we study monotone grid drawings of planar graphs in a variable
embedding setting. We show that every connected planar graph of vertices
has a monotone grid drawing on a grid of size , and such a
drawing can be found in O(n) time
Assessment of the effectiveness of head only and back-of-the-head electrical stunning of chickens
The study assesses the effectiveness of reversible head-only and back-of-the-head electrical stunning of chickens using 130–950 mA per bird at 50 Hz AC
A Planarity Test via Construction Sequences
Optimal linear-time algorithms for testing the planarity of a graph are
well-known for over 35 years. However, these algorithms are quite involved and
recent publications still try to give simpler linear-time tests. We give a
simple reduction from planarity testing to the problem of computing a certain
construction of a 3-connected graph. The approach is different from previous
planarity tests; as key concept, we maintain a planar embedding that is
3-connected at each point in time. The algorithm runs in linear time and
computes a planar embedding if the input graph is planar and a
Kuratowski-subdivision otherwise
Decision Problems For Convex Languages
In this paper we examine decision problems associated with various classes of
convex languages, studied by Ang and Brzozowski (under the name "continuous
languages"). We show that we can decide whether a given language L is prefix-,
suffix-, factor-, or subword-convex in polynomial time if L is represented by a
DFA, but that the problem is PSPACE-hard if L is represented by an NFA. In the
case that a regular language is not convex, we prove tight upper bounds on the
length of the shortest words demonstrating this fact, in terms of the number of
states of an accepting DFA. Similar results are proved for some subclasses of
convex languages: the prefix-, suffix-, factor-, and subword-closed languages,
and the prefix-, suffix-, factor-, and subword-free languages.Comment: preliminary version. This version corrected one typo in Section
2.1.1, line
К вопросу об оценке противокоррозионной эффективности ингибиторов атмосферной коррозии
Розробка, дослідження захисних антикорозійних властивостей і визначення механізму дії інгібіторів атмосферної корозії, призначених для захисту металу з тонкими шарами іржі, потребує проведення натурних та прискорених корозійних випробувань. Оскільки у більшості випадків цей процес довготривалий, то для швидкого визначення антикорозійної ефективності інгібіторів корозії розроблена методика їх прискорених випробувань. Методика полягає у визначенні захисних властивостей інгібітору шляхом зняття поляризаційних кривих у нейтральному середовищі на металі з продуктами атмосферної корозії та захисною плівкою.Development, research of protective anticorrosive properties and determination of mechanism of action of atmospheric corrosion inhibitors for the protection of metal with thin layers of rust demands carrying out of the natural and accelerated corrosion tests. As in most cases this process long, for rapid determination of anticorrosive efficiency of corrosion inhibitors the new method of their accelerated tests is developed. A method consists in definition of protective ability by removal of polarization curves on a metal with the products of atmospheric corrosion and protective film in a neutral environment
The zero exemplar distance problem
Given two genomes with duplicate genes, \textsc{Zero Exemplar Distance} is
the problem of deciding whether the two genomes can be reduced to the same
genome without duplicate genes by deleting all but one copy of each gene in
each genome. Blin, Fertin, Sikora, and Vialette recently proved that
\textsc{Zero Exemplar Distance} for monochromosomal genomes is NP-hard even if
each gene appears at most two times in each genome, thereby settling an
important open question on genome rearrangement in the exemplar model. In this
paper, we give a very simple alternative proof of this result. We also study
the problem \textsc{Zero Exemplar Distance} for multichromosomal genomes
without gene order, and prove the analogous result that it is also NP-hard even
if each gene appears at most two times in each genome. For the positive
direction, we show that both variants of \textsc{Zero Exemplar Distance} admit
polynomial-time algorithms if each gene appears exactly once in one genome and
at least once in the other genome. In addition, we present a polynomial-time
algorithm for the related problem \textsc{Exemplar Longest Common Subsequence}
in the special case that each mandatory symbol appears exactly once in one
input sequence and at least once in the other input sequence. This answers an
open question of Bonizzoni et al. We also show that \textsc{Zero Exemplar
Distance} for multichromosomal genomes without gene order is fixed-parameter
tractable if the parameter is the maximum number of chromosomes in each genome.Comment: Strengthened and reorganize
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