Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Semantic Width and the Fixed-Parameter Tractability of Constraint
  Satisfaction Problems   Constraint satisfaction problems (CSPs) are an important formal framework for
the uniform treatment of various prominent AI tasks, e.g., coloring or
scheduling problems. Solving CSPs is, in general, known to be NP-complete and
fixed-parameter intractable when parameterized by their constraint scopes. We
give a characterization of those classes of CSPs for which the problem becomes
fixed-parameter tractable.
  Our characterization significantly increases the utility of the CSP framework
by making it possible to decide the fixed-parameter tractability of problems
via their CSP formulations.
  We further extend our characterization to the evaluation of unions of
conjunctive queries, a fundamental problem in databases. Furthermore, we
provide some new insight on the frontier of PTIME solvability of CSPs.
  In particular, we observe that bounded fractional hypertree width is more
general than bounded hypertree width only for classes that exhibit a certain
type of exponential growth.
  The presented work resolves a long-standing open problem and yields powerful
new tools for complexity research in AI and database theory.

35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
2
The categories of this paper are: math
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat