1,363 research outputs found
A Proof Strategy Language and Proof Script Generation for Isabelle/HOL
We introduce a language, PSL, designed to capture high level proof strategies
in Isabelle/HOL. Given a strategy and a proof obligation, PSL's runtime system
generates and combines various tactics to explore a large search space with low
memory usage. Upon success, PSL generates an efficient proof script, which
bypasses a large part of the proof search. We also present PSL's monadic
interpreter to show that the underlying idea of PSL is transferable to other
ITPs.Comment: This paper has been submitted to CADE2
XWeB: the XML Warehouse Benchmark
With the emergence of XML as a standard for representing business data, new
decision support applications are being developed. These XML data warehouses
aim at supporting On-Line Analytical Processing (OLAP) operations that
manipulate irregular XML data. To ensure feasibility of these new tools,
important performance issues must be addressed. Performance is customarily
assessed with the help of benchmarks. However, decision support benchmarks do
not currently support XML features. In this paper, we introduce the XML
Warehouse Benchmark (XWeB), which aims at filling this gap. XWeB derives from
the relational decision support benchmark TPC-H. It is mainly composed of a
test data warehouse that is based on a unified reference model for XML
warehouses and that features XML-specific structures, and its associate XQuery
decision support workload. XWeB's usage is illustrated by experiments on
several XML database management systems
Matching LOFAR sources across radio bands
Aims. With the recent preliminary release of the LOFAR LBA Sky Survey
(LoLSS), the first wide-area, ultra-low frequency observations from LOFAR were
published. Our aim is to combine this data set with other surveys at higher
frequencies to study the spectral properties of a large sample of radio
sources. Methods. We present a new cross-matching algorithm taking into account
the sizes of the radio sources and apply it to the LoLSS-PR, LoTSS-DR1,
LoTSS-DR2 (all LOFAR), TGSS-ADR1 (GMRT), WENSS (WSRT) and NVSS (VLA)
catalogues. We then study the number of matched counterparts for LoLSS radio
sources and their spectral properties. Results. We find counterparts for 22 607
(89.5%) LoLSS sources. The remaining 2 640 sources (10.5%) are identified
either as an artefact in the LoLSS survey (3.6%) or flagged due to their
closeness to bright sources (6.9%). We find an average spectral index of
between LoLSS and NVSS. Between LoLSS and LoTSS-DR2
we find . The average spectral index is flux density
independent above mJy. Comparison of the spectral slopes from
LoLSS--LoTSS-DR2 with LoTSS-DR2--NVSS indicates that the probed population of
radio sources exhibits evidence for a negative spectral curvature.Comment: 13 pages, 22 figures and 2 tables. Accepted for publication in A&
Early Miocene gastropod and ectothermic vertebrate remains from the Lesvos Petrified Forest (Greece)
The Lesvos Petrified Forest (western Lesvos, Greece) has long been famous for its plant fossils. Recently, one proboscidean (from the Gavathas locality) and seven micromammalian species (from the Lapsarna locality) were described; these were the first animals to be found in the Early Miocene subtropical forest. For the first time, a fauna of gastropods and ectothermic vertebrates from the Lapsarna locality is now available. This fauna derives from lacustrine sediments under the pyroclastic material that contains the petrified plants. Based on fragmented mollusc remains, isolated fish pharyngeal teeth and utricular otoliths (lapilli), fragmented amphibian vertebrae and a tooth-bearing element, and reptile fragmented dentaries, teeth, osteoderms and vertebrae, the presence of eight freshwater and three terrestrial gastropod species, three freshwater cyprinid species, and two amphibian and five reptile taxa has been confirmed. Stratigraphical and radiometric data suggest an age older than 18.4 ± 0.5 Ma (latest Early Miocene), in good agreement with the faunal composition. This paper is the first report of the concurrent presence of three cyprinid fish species in a Greek Early Miocene locality, as well as the first documentation of an Early Miocene proteid amphibian in southeastern Europe. The present findings represent one of the best- documented Early Miocene gastropod and fish faunas in the Aegean/southern Balkans, thus adding to our knowledge of Early Miocene amphibians and reptiles from that region and providing valuable information on the local subtropical ecosystem
Mining State-Based Models from Proof Corpora
Interactive theorem provers have been used extensively to reason about
various software/hardware systems and mathematical theorems. The key challenge
when using an interactive prover is finding a suitable sequence of proof steps
that will lead to a successful proof requires a significant amount of human
intervention. This paper presents an automated technique that takes as input
examples of successful proofs and infers an Extended Finite State Machine as
output. This can in turn be used to generate proofs of new conjectures. Our
preliminary experiments show that the inferred models are generally accurate
(contain few false-positive sequences) and that representing existing proofs in
such a way can be very useful when guiding new ones.Comment: To Appear at Conferences on Intelligent Computer Mathematics 201
Targeted analysis of polymorphic loci from low-coverage shotgun sequence data allows accurate genotyping of HLA genes in historical human populations
The highly polymorphic human leukocyte antigen (HLA) plays a crucial role in adaptive immunity and is associated with various complex diseases. Accurate analysis of HLA genes using ancient DNA (aDNA) data is crucial for understanding their role in human adaptation to pathogens. Here, we describe the TARGT pipeline for targeted analysis of polymorphic loci from low-coverage shotgun sequence data. The pipeline was successfully applied to medieval aDNA samples and validated using both simulated aDNA and modern empirical sequence data from the 1000 Genomes Project. Thus the TARGT pipeline enables accurate analysis of HLA polymorphisms in historical (and modern) human populations
A Human-Oriented Term Rewriting System
© Springer Nature Switzerland AG 2019. We introduce a fully automatic system, implemented in the Lean theorem prover, that solves equality problems of everyday mathematics. Our overriding priority in devising the system is that it should construct proofs of equality in a way that is similar to that of humans. A second goal is that the methods it uses should be domain independent. The basic strategy of the system is to operate with a subtask stack: whenever there is no clear way of making progress towards the task at the top of the stack, the program finds a promising subtask, such as rewriting a subterm, and places that at the top of the stack instead. Heuristics guide the choice of promising subtasks and the rewriting process. This makes proofs more human-like by breaking the problem into tasks in the way that a human would. We show that our system can prove equality theorems simply, without having to preselect or orient rewrite rules as in standard theorem provers, and without having to invoke heavy duty tools for performing simple reasoning
A Survey of Satisfiability Modulo Theory
Satisfiability modulo theory (SMT) consists in testing the satisfiability of
first-order formulas over linear integer or real arithmetic, or other theories.
In this survey, we explain the combination of propositional satisfiability and
decision procedures for conjunctions known as DPLL(T), and the alternative
"natural domain" approaches. We also cover quantifiers, Craig interpolants,
polynomial arithmetic, and how SMT solvers are used in automated software
analysis.Comment: Computer Algebra in Scientific Computing, Sep 2016, Bucharest,
Romania. 201
Photoinduced 3D orientational order in side chain liquid crystalline azopolymers
We apply experimental technique based on the combination of methods dealing
with principal refractive indices and absorption coefficients to study the
photoinduced 3D orientational order in the films of liquid crystalline (LC)
azopolymers. The technique is used to identify 3D orientational configurations
of trans azobenzene chromophores and to characterize the degree of ordering in
terms of order parameters. We study two types of LC azopolymers which form
structures with preferred in-plane and out-of-plane alignment of
azochromophores, correspondingly. Using irradiation with the polarized light of
two different wavelengths we find that the kinetics of photoinduced anisotropy
can be dominated by either photo-reorientation or photoselection mechanisms
depending on the wavelength. We formulate the phenomenological model describing
the kinetics of photoinduced anisotropy in terms of the isomer concentrations
and the order parameter tensor. We present the numerical results for absorption
coefficients that are found to be in good agreement with the experimental data.
The model is also used to interpret the effect of changing the mechanism with
the wavelength of the pumping light.Comment: uses revtex4 28 pages, 10 figure
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