23,563 research outputs found
Sketched Answer Set Programming
Answer Set Programming (ASP) is a powerful modeling formalism for
combinatorial problems. However, writing ASP models is not trivial. We propose
a novel method, called Sketched Answer Set Programming (SkASP), aiming at
supporting the user in resolving this issue. The user writes an ASP program
while marking uncertain parts open with question marks. In addition, the user
provides a number of positive and negative examples of the desired program
behaviour. The sketched model is rewritten into another ASP program, which is
solved by traditional methods. As a result, the user obtains a functional and
reusable ASP program modelling her problem. We evaluate our approach on 21 well
known puzzles and combinatorial problems inspired by Karp's 21 NP-complete
problems and demonstrate a use-case for a database application based on ASP.Comment: 15 pages, 11 figures; to appear in ICTAI 201
Breaking Instance-Independent Symmetries In Exact Graph Coloring
Code optimization and high level synthesis can be posed as constraint
satisfaction and optimization problems, such as graph coloring used in register
allocation. Graph coloring is also used to model more traditional CSPs relevant
to AI, such as planning, time-tabling and scheduling. Provably optimal
solutions may be desirable for commercial and defense applications.
Additionally, for applications such as register allocation and code
optimization, naturally-occurring instances of graph coloring are often small
and can be solved optimally. A recent wave of improvements in algorithms for
Boolean satisfiability (SAT) and 0-1 Integer Linear Programming (ILP) suggests
generic problem-reduction methods, rather than problem-specific heuristics,
because (1) heuristics may be upset by new constraints, (2) heuristics tend to
ignore structure, and (3) many relevant problems are provably inapproximable.
Problem reductions often lead to highly symmetric SAT instances, and
symmetries are known to slow down SAT solvers. In this work, we compare several
avenues for symmetry breaking, in particular when certain kinds of symmetry are
present in all generated instances. Our focus on reducing CSPs to SAT allows us
to leverage recent dramatic improvement in SAT solvers and automatically
benefit from future progress. We can use a variety of black-box SAT solvers
without modifying their source code because our symmetry-breaking techniques
are static, i.e., we detect symmetries and add symmetry breaking predicates
(SBPs) during pre-processing.
An important result of our work is that among the types of
instance-independent SBPs we studied and their combinations, the simplest and
least complete constructions are the most effective. Our experiments also
clearly indicate that instance-independent symmetries should mostly be
processed together with instance-specific symmetries rather than at the
specification level, contrary to what has been suggested in the literature
A reusable iterative optimization software library to solve combinatorial problems with approximate reasoning
Real world combinatorial optimization problems such as scheduling are
typically too complex to solve with exact methods. Additionally, the problems
often have to observe vaguely specified constraints of different importance,
the available data may be uncertain, and compromises between antagonistic
criteria may be necessary. We present a combination of approximate reasoning
based constraints and iterative optimization based heuristics that help to
model and solve such problems in a framework of C++ software libraries called
StarFLIP++. While initially developed to schedule continuous caster units in
steel plants, we present in this paper results from reusing the library
components in a shift scheduling system for the workforce of an industrial
production plant.Comment: 33 pages, 9 figures; for a project overview see
http://www.dbai.tuwien.ac.at/proj/StarFLIP
Working Notes from the 1992 AAAI Spring Symposium on Practical Approaches to Scheduling and Planning
The symposium presented issues involved in the development of scheduling systems that can deal with resource and time limitations. To qualify, a system must be implemented and tested to some degree on non-trivial problems (ideally, on real-world problems). However, a system need not be fully deployed to qualify. Systems that schedule actions in terms of metric time constraints typically represent and reason about an external numeric clock or calendar and can be contrasted with those systems that represent time purely symbolically. The following topics are discussed: integrating planning and scheduling; integrating symbolic goals and numerical utilities; managing uncertainty; incremental rescheduling; managing limited computation time; anytime scheduling and planning algorithms, systems; dependency analysis and schedule reuse; management of schedule and plan execution; and incorporation of discrete event techniques
Representation-Selection for Constraint Satisfaction Problems: A Case Study Using n-Queens
https://deepblue.lib.umich.edu/bitstream/2027.42/154179/1/39015100081804.pd
Universalization or localization? Issues of knowledge legitimation in comaprative education
The endeavor to unite the universal and the accidental in both, the physical and the social world into one theoretical framework – the idea of such a unity can be found already in the Chinese concept of Tao – dates back in the modern culture to the Enlightenment. Such a unified knowledge came to be understood as a potential tool of forecasting and controlling societal progress. All through the positivistic 19th century, comparativists followed Marc-Antoine Jullien de Paris, who thought educational comparison should become an exact science whose outcomes could be used anywhere and transplanted to any place. It was Michael Sadler who as the first comparative educationalist strictly refused the idea of cultural and institutional borrowing. Under his influence comparative education focused on the variations unique to the single countries and to the factors underlying these variations. Even the later emerging functionalist method remained in the tradition of a „one-dimensional logic“, which, as Marcuse alleged, was inseparably connected with the rationale of domination of nature and society. It is only the postmodern sight, which – without giving up the humanistic ideas of modernity which originated in Western modernization – opens possibilities to enter a cross cultural dialogue and to accept multiple theoretical realities. (DIPF/Orig.)Der Beitrag bietet einen breiten Überblick über grundlegende Tendenzen in der historischen Entwicklung von Vergleichender Erziehungswissenschaft. Dabei unterliegt der Darstellung implizit und explizit durchgängig das Bewußtsein, daß vergleichende Wissenschaft im weitesten Sinne weder ein Monopol der jüngsten Epoche noch etwa eines einzigen Kulturraums darstellt. Mit seiner analytischen, aber auch normativen Interpretation von gegenwärtigen Tendenzen postmodernen Denkens sieht er die Möglichkeit eines transkulturellen Dialogs über die Weiterentwicklung und Erweiterung der etablierten (westlichen) Vergleichenden (Erziehungs-)Wissenschaft. (DIPF/Orig.
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