1,323 research outputs found
Comparative Analysis of Deterministic and Nondeterministic Decision Trees for Decision Tables from Closed Classes
In this paper, we consider classes of decision tables with many-valued
decisions closed under operations of removal of columns, changing of decisions,
permutation of columns, and duplication of columns. We study relationships
among three parameters of these tables: the complexity of a decision table (if
we consider the depth of decision trees, then the complexity of a decision
table is the number of columns in it), the minimum complexity of a
deterministic decision tree, and the minimum complexity of a nondeterministic
decision tree. We consider rough classification of functions characterizing
relationships and enumerate all possible seven types of the relationships
Generalizing input-driven languages: theoretical and practical benefits
Regular languages (RL) are the simplest family in Chomsky's hierarchy. Thanks
to their simplicity they enjoy various nice algebraic and logic properties that
have been successfully exploited in many application fields. Practically all of
their related problems are decidable, so that they support automatic
verification algorithms. Also, they can be recognized in real-time.
Context-free languages (CFL) are another major family well-suited to
formalize programming, natural, and many other classes of languages; their
increased generative power w.r.t. RL, however, causes the loss of several
closure properties and of the decidability of important problems; furthermore
they need complex parsing algorithms. Thus, various subclasses thereof have
been defined with different goals, spanning from efficient, deterministic
parsing to closure properties, logic characterization and automatic
verification techniques.
Among CFL subclasses, so-called structured ones, i.e., those where the
typical tree-structure is visible in the sentences, exhibit many of the
algebraic and logic properties of RL, whereas deterministic CFL have been
thoroughly exploited in compiler construction and other application fields.
After surveying and comparing the main properties of those various language
families, we go back to operator precedence languages (OPL), an old family
through which R. Floyd pioneered deterministic parsing, and we show that they
offer unexpected properties in two fields so far investigated in totally
independent ways: they enable parsing parallelization in a more effective way
than traditional sequential parsers, and exhibit the same algebraic and logic
properties so far obtained only for less expressive language families
Evolution of interface binding strengths in simplified model of protein quaternary structure.
The self-assembly of proteins into protein quaternary structures is of fundamental importance to many biological processes, and protein misassembly is responsible for a wide range of proteopathic diseases. In recent years, abstract lattice models of protein self-assembly have been used to simulate the evolution and assembly of protein quaternary structure, and to provide a tractable way to study the genotype-phenotype map of such systems. Here we generalize these models by representing the interfaces as mutable binary strings. This simple change enables us to model the evolution of interface strengths, interface symmetry, and deterministic assembly pathways. Using the generalized model we are able to reproduce two important results established for real protein complexes: The first is that protein assembly pathways are under evolutionary selection to minimize misassembly. The second is that the assembly pathway of a complex mirrors its evolutionary history, and that both can be derived from the relative strengths of interfaces. These results demonstrate that the generalized lattice model offers a powerful new idealized framework to facilitate the study of protein self-assembly processes and their evolution
Beyond Language Equivalence on Visibly Pushdown Automata
We study (bi)simulation-like preorder/equivalence checking on the class of
visibly pushdown automata and its natural subclasses visibly BPA (Basic Process
Algebra) and visibly one-counter automata. We describe generic methods for
proving complexity upper and lower bounds for a number of studied preorders and
equivalences like simulation, completed simulation, ready simulation, 2-nested
simulation preorders/equivalences and bisimulation equivalence. Our main
results are that all the mentioned equivalences and preorders are
EXPTIME-complete on visibly pushdown automata, PSPACE-complete on visibly
one-counter automata and P-complete on visibly BPA. Our PSPACE lower bound for
visibly one-counter automata improves also the previously known DP-hardness
results for ordinary one-counter automata and one-counter nets. Finally, we
study regularity checking problems for visibly pushdown automata and show that
they can be decided in polynomial time.Comment: Final version of paper, accepted by LMC
Bounds on Depth of Decision Trees Derived from Decision Rule Systems
Systems of decision rules and decision trees are widely used as a means for
knowledge representation, as classifiers, and as algorithms. They are among the
most interpretable models for classifying and representing knowledge. The study
of relationships between these two models is an important task of computer
science. It is easy to transform a decision tree into a decision rule system.
The inverse transformation is a more difficult task. In this paper, we study
unimprovable upper and lower bounds on the minimum depth of decision trees
derived from decision rule systems depending on the various parameters of these
systems
A Survey of Monte Carlo Tree Search Methods
Monte Carlo tree search (MCTS) is a recently proposed search method that combines the precision of tree search with the generality of random sampling. It has received considerable interest due to its spectacular success in the difficult problem of computer Go, but has also proved beneficial in a range of other domains. This paper is a survey of the literature to date, intended to provide a snapshot of the state of the art after the first five years of MCTS research. We outline the core algorithm's derivation, impart some structure on the many variations and enhancements that have been proposed, and summarize the results from the key game and nongame domains to which MCTS methods have been applied. A number of open research questions indicate that the field is ripe for future work
In Memoriam, Solomon Marcus
This book commemorates Solomon Marcus’s fifth death anniversary with a selection of articles in mathematics, theoretical computer science, and physics written by authors who work in Marcus’s research fields, some of whom have been influenced by his results and/or have collaborated with him
Reasoning about Regular Properties: A Comparative Study
Several new algorithms for deciding emptiness of Boolean combinations of
regular languages and of languages of alternating automata (AFA) have been
proposed recently, especially in the context of analysing regular expressions
and in string constraint solving. The new algorithms demonstrated a significant
potential, but they have never been systematically compared, neither among each
other nor with the state-of-the art implementations of existing
(non)deterministic automata-based methods. In this paper, we provide the first
such comparison as well as an overview of the existing algorithms and their
implementations. We collect a diverse benchmark mostly originating in or
related to practical problems from string constraint solving, analysing LTL
properties, and regular model checking, and evaluate collected implementations
on it. The results reveal the best tools and hint on what the best algorithms
and implementation techniques are. Roughly, although some advanced algorithms
are fast, such as antichain algorithms and reductions to IC3/PDR, they are not
as overwhelmingly dominant as sometimes presented and there is no clear winner.
The simplest NFA-based technology may be actually the best choice, depending on
the problem source and implementation style. Our findings should be highly
relevant for development of these techniques as well as for related fields such
as string constraint solving
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