1,191 research outputs found
The Case for Perspicuous Programming
This essay examines the nature of programs, classifies the traditional or enigmatic styles of programming, distinguishing template, prose and literate styles; notes the contrast between batch programs and interactive programs; and highlights the advantages of giving priority in developing interactive programs to the online documentation, and proposes that this documentation should be the principal target of development, with the executable program code being regarded of secondary and consequent
Specific-to-General Learning for Temporal Events with Application to Learning Event Definitions from Video
We develop, analyze, and evaluate a novel, supervised, specific-to-general
learner for a simple temporal logic and use the resulting algorithm to learn
visual event definitions from video sequences. First, we introduce a simple,
propositional, temporal, event-description language called AMA that is
sufficiently expressive to represent many events yet sufficiently restrictive
to support learning. We then give algorithms, along with lower and upper
complexity bounds, for the subsumption and generalization problems for AMA
formulas. We present a positive-examples--only specific-to-general learning
method based on these algorithms. We also present a polynomial-time--computable
``syntactic'' subsumption test that implies semantic subsumption without being
equivalent to it. A generalization algorithm based on syntactic subsumption can
be used in place of semantic generalization to improve the asymptotic
complexity of the resulting learning algorithm. Finally, we apply this
algorithm to the task of learning relational event definitions from video and
show that it yields definitions that are competitive with hand-coded ones
Perspicuity and Granularity in Refinement
This paper reconsiders refinements which introduce actions on the concrete
level which were not present at the abstract level. It draws a distinction
between concrete actions which are "perspicuous" at the abstract level, and
changes of granularity of actions between different levels of abstraction.
The main contribution of this paper is in exploring the relation between
these different methods of "action refinement", and the basic refinement
relation that is used. In particular, it shows how the "refining skip" method
is incompatible with failures-based refinement relations, and consequently some
decisions in designing Event-B refinement are entangled.Comment: In Proceedings Refine 2011, arXiv:1106.348
Three New Probabilistic Models for Dependency Parsing: An Exploration
After presenting a novel O(n^3) parsing algorithm for dependency grammar, we
develop three contrasting ways to stochasticize it. We propose (a) a lexical
affinity model where words struggle to modify each other, (b) a sense tagging
model where words fluctuate randomly in their selectional preferences, and (c)
a generative model where the speaker fleshes out each word's syntactic and
conceptual structure without regard to the implications for the hearer. We also
give preliminary empirical results from evaluating the three models' parsing
performance on annotated Wall Street Journal training text (derived from the
Penn Treebank). In these results, the generative (i.e., top-down) model
performs significantly better than the others, and does about equally well at
assigning part-of-speech tags.Comment: 6 pages, LaTeX 2.09 packaged with 4 .eps files, also uses colap.sty
and acl.bs
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