229,064 research outputs found
Spurious, Emergent Laws in Number Worlds
We study some aspects of the emergence of logos from chaos on a basal model
of the universe using methods and techniques from algorithmic information and
Ramsey theories. Thereby an intrinsic and unusual mixture of meaningful and
spurious, emerging laws surfaces. The spurious, emergent laws abound, they can
be found almost everywhere. In accord with the ancient Greek theogony one could
say that logos, the Gods and the laws of the universe, originate from "the
void," or from chaos, a picture which supports the unresolvable/irreducible
lawless hypothesis. The analysis presented in this paper suggests that the
"laws" discovered in science correspond merely to syntactical correlations, are
local and not universal.Comment: 24 pages, invited contribution to "Contemporary Natural Philosophy
and Philosophies - Part 2" - Special Issue of the journal Philosophie
Volume-Enclosing Surface Extraction
In this paper we present a new method, which allows for the construction of
triangular isosurfaces from three-dimensional data sets, such as 3D image data
and/or numerical simulation data that are based on regularly shaped, cubic
lattices. This novel volume-enclosing surface extraction technique, which has
been named VESTA, can produce up to six different results due to the nature of
the discretized 3D space under consideration. VESTA is neither template-based
nor it is necessarily required to operate on 2x2x2 voxel cell neighborhoods
only. The surface tiles are determined with a very fast and robust construction
technique while potential ambiguities are detected and resolved. Here, we
provide an in-depth comparison between VESTA and various versions of the
well-known and very popular Marching Cubes algorithm for the very first time.
In an application section, we demonstrate the extraction of VESTA isosurfaces
for various data sets ranging from computer tomographic scan data to simulation
data of relativistic hydrodynamic fireball expansions.Comment: 24 pages, 33 figures, 4 tables, final versio
Revisiting the Rice Theorem of Cellular Automata
A cellular automaton is a parallel synchronous computing model, which
consists in a juxtaposition of finite automata whose state evolves according to
that of their neighbors. It induces a dynamical system on the set of
configurations, i.e. the infinite sequences of cell states. The limit set of
the cellular automaton is the set of configurations which can be reached
arbitrarily late in the evolution.
In this paper, we prove that all properties of limit sets of cellular
automata with binary-state cells are undecidable, except surjectivity. This is
a refinement of the classical "Rice Theorem" that Kari proved on cellular
automata with arbitrary state sets.Comment: 12 pages conference STACS'1
From algebra to logic: there and back again -- the story of a hierarchy
This is an extended survey of the results concerning a hierarchy of languages
that is tightly connected with the quantifier alternation hierarchy within the
two-variable fragment of first order logic of the linear order.Comment: Developments in Language Theory 2014, Ekaterinburg : Russian
Federation (2014
Algorithmic Randomness as Foundation of Inductive Reasoning and Artificial Intelligence
This article is a brief personal account of the past, present, and future of
algorithmic randomness, emphasizing its role in inductive inference and
artificial intelligence. It is written for a general audience interested in
science and philosophy. Intuitively, randomness is a lack of order or
predictability. If randomness is the opposite of determinism, then algorithmic
randomness is the opposite of computability. Besides many other things, these
concepts have been used to quantify Ockham's razor, solve the induction
problem, and define intelligence.Comment: 9 LaTeX page
Speeding-up Dynamic Programming with Representative Sets - An Experimental Evaluation of Algorithms for Steiner Tree on Tree Decompositions
Dynamic programming on tree decompositions is a frequently used approach to
solve otherwise intractable problems on instances of small treewidth. In recent
work by Bodlaender et al., it was shown that for many connectivity problems,
there exist algorithms that use time, linear in the number of vertices, and
single exponential in the width of the tree decomposition that is used. The
central idea is that it suffices to compute representative sets, and these can
be computed efficiently with help of Gaussian elimination.
In this paper, we give an experimental evaluation of this technique for the
Steiner Tree problem. A comparison of the classic dynamic programming algorithm
and the improved dynamic programming algorithm that employs the table reduction
shows that the new approach gives significant improvements on the running time
of the algorithm and the size of the tables computed by the dynamic programming
algorithm, and thus that the rank based approach from Bodlaender et al. does
not only give significant theoretical improvements but also is a viable
approach in a practical setting, and showcases the potential of exploiting the
idea of representative sets for speeding up dynamic programming algorithms
Equilibrium Clusters in Concentrated Lysozyme Protein Solutions
We have studied the structure of salt-free lysozyme at 293 K and pH 7.8 using
molecular simulations and experimental SAXS effective potentials between
proteins at three volume fractions, 0.012, 0.033, and 0.12. We found that the
structure of lysozyme near physiological conditions strongly depends on the
volume fraction of proteins. The studied lysozyme solutions are dominated by
monomers only for <0.012; for the strong dilution 70% of proteins are in a form
of monomers. For 0.033 only 20% of proteins do not belong to a cluster. The
clusters are mainly elongated. For 0.12 almost no individual particles exits,
and branched, irregular clusters of large extent appear. Our simulation study
provides new insight into the formation of equilibrium clusters in charged
protein solutions near physiological conditions
- …