3,167 research outputs found
Taming Numbers and Durations in the Model Checking Integrated Planning System
The Model Checking Integrated Planning System (MIPS) is a temporal least
commitment heuristic search planner based on a flexible object-oriented
workbench architecture. Its design clearly separates explicit and symbolic
directed exploration algorithms from the set of on-line and off-line computed
estimates and associated data structures. MIPS has shown distinguished
performance in the last two international planning competitions. In the last
event the description language was extended from pure propositional planning to
include numerical state variables, action durations, and plan quality objective
functions. Plans were no longer sequences of actions but time-stamped
schedules. As a participant of the fully automated track of the competition,
MIPS has proven to be a general system; in each track and every benchmark
domain it efficiently computed plans of remarkable quality. This article
introduces and analyzes the most important algorithmic novelties that were
necessary to tackle the new layers of expressiveness in the benchmark problems
and to achieve a high level of performance. The extensions include critical
path analysis of sequentially generated plans to generate corresponding optimal
parallel plans. The linear time algorithm to compute the parallel plan bypasses
known NP hardness results for partial ordering by scheduling plans with respect
to the set of actions and the imposed precedence relations. The efficiency of
this algorithm also allows us to improve the exploration guidance: for each
encountered planning state the corresponding approximate sequential plan is
scheduled. One major strength of MIPS is its static analysis phase that grounds
and simplifies parameterized predicates, functions and operators, that infers
knowledge to minimize the state description length, and that detects domain
object symmetries. The latter aspect is analyzed in detail. MIPS has been
developed to serve as a complete and optimal state space planner, with
admissible estimates, exploration engines and branching cuts. In the
competition version, however, certain performance compromises had to be made,
including floating point arithmetic, weighted heuristic search exploration
according to an inadmissible estimate and parameterized optimization
ProteinsPlus: a web portal for structure analysis of macromolecules
With currently more than 126 000 publicly available structures and an
increasing growth rate, the Protein Data Bank constitutes a rich data source
for structure-driven research in fields like drug discovery, crop science and
biotechnology in general. Typical workflows in these areas involve manifold
computational tools for the analysis and prediction of molecular functions.
Here, we present the ProteinsPlus web server that offers a unified easy-to-use
interface to a broad range of tools for the early phase of structure-based
molecular modeling. This includes solutions for commonly required pre-
processing tasks like structure quality assessment (EDIA), hydrogen placement
(Protoss) and the search for alternative conformations (SIENA). Beyond that,
it also addresses frequent problems as the generation of 2D-interaction
diagrams (PoseView), protein–protein interface classification (HyPPI) as well
as automatic pocket detection and druggablity assessment (DoGSiteScorer). The
unified ProteinsPlus interface covering all featured approaches provides
various facilities for intuitive input and result visualization, case-specific
parameterization and download options for further processing. Moreover, its
generalized workflow allows the user a quick familiarization with the
different tools. ProteinsPlus also stores the calculated results temporarily
for future request and thus facilitates convenient result communication and
re-access. The server is freely available at http://proteins.plus
On Formal Methods for Large-Scale Product Configuration
<p>In product development companies mass customization is widely used to achieve better customer satisfaction while keeping costs down. To efficiently implement mass customization, product platforms are often used. A product platform allows building a wide range of products from a set of predefined components. The process of matching these components to customers' needs is called product configuration. Not all components can be combined with each other due to restrictions of various kinds, for example, geometrical, marketing and legal reasons. Product design engineers develop configuration constraints to describe such restrictions. The number of constraints and the complexity of the relations between them are immense for complex product like a vehicle. Thus, it is both error-prone and time consuming to analyze, author and verify the constraints manually. Software tools based on formal methods can help engineers to avoid making errors when working with configuration constraints, thus design a correct product faster.</p>
<p>This thesis introduces a number of formal methods to help engineers maintain, verify and analyze product configuration constraints. These methods provide automatic verification of constraints and computational support for analyzing and refactoring constraints. The methods also allow verifying the correctness of one specific type of constraints, item usage rules, for sets of mutually-exclusive required items, and automatic verification of equivalence of different formulations of the constraints. The thesis also introduces three methods for efficient enumeration of valid partial configurations, with benchmarking of the methods on an industrial dataset.</p>
<p>Handling large-scale industrial product configuration problems demands high efficiency from the software methods. This thesis investigates a number of search-based and knowledge-compilation-based methods for working with large product configuration instances, including Boolean satisfiability solvers, binary decision diagrams and decomposable negation normal form. This thesis also proposes a novel method based on supervisory control theory for efficient reasoning about product configuration data. The methods were implemented in a tool, to investigate the applicability of the methods for handling large product configuration problems. It was found that search-based Boolean satisfiability solvers with incremental capabilities are well suited for industrial configuration problems.</p>
<p>The methods proposed in this thesis exhibit good performance on practical configuration problems, and have a potential to be implemented in industry to support product design engineers in creating and maintaining configuration constraints, and speed up the development of product platforms and new products.</p
Type-elimination-based reasoning for the description logic SHIQbs using decision diagrams and disjunctive datalog
We propose a novel, type-elimination-based method for reasoning in the
description logic SHIQbs including DL-safe rules. To this end, we first
establish a knowledge compilation method converting the terminological part of
an ALCIb knowledge base into an ordered binary decision diagram (OBDD) which
represents a canonical model. This OBDD can in turn be transformed into
disjunctive Datalog and merged with the assertional part of the knowledge base
in order to perform combined reasoning. In order to leverage our technique for
full SHIQbs, we provide a stepwise reduction from SHIQbs to ALCIb that
preserves satisfiability and entailment of positive and negative ground facts.
The proposed technique is shown to be worst case optimal w.r.t. combined and
data complexity and easily admits extensions with ground conjunctive queries.Comment: 38 pages, 3 figures, camera ready version of paper accepted for
publication in Logical Methods in Computer Scienc
SuSpect: a Fortran Code for the Supersymmetric and Higgs Particle Spectrum in the MSSM
We present the Fortran code SuSpect version 2.3, which calculates the
Supersymmetric and Higgs particle spectrum in the Minimal Supersymmetric
Standard Model (MSSM). The calculation can be performed in constrained models
with universal boundary conditions at high scales such as the gravity (mSUGRA),
anomaly (AMSB) or gauge (GMSB) mediated breaking models, but also in the
non-universal MSSM case with R-parity and CP conservation. Care has been taken
to treat important features such as the renormalization group evolution of
parameters between low and high energy scales, the consistent implementation of
radiative electroweak symmetry breaking and the calculation of the physical
masses of the Higgs bosons and supersymmetric particles taking into account the
dominant radiative corrections. Some checks of important theoretical and
experimental features, such as the absence of non desired minima, large
fine-tuning in the electroweak symmetry breaking condition, as well as
agreement with precision measurements can be performed. The program is user
friendly, simple to use, self-contained and can easily be linked with other
codes; it is rather fast and flexible, thus allowing scans of the parameter
space with several possible options and choices for model assumptions and
approximations.Comment: 44 pages, 1 figure. Program updated and text shortened. The program
can be found at http://www.lpta.univ-montp2.fr/~kneur/Suspec
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