If the effective focal length of a growing eye is modified by spectacle lenses, the eye compensates by altering its growth, thereby keeping images in focus, a process we presume is similar to normal emmetropization. Using chicks, we have investigated how much visual exposure the eye needs to exhibit the two principal components of ocular compensation: altered rate of elongation (a scleral mecha...

Article history: Received 20 March 2009 Received in revised form 20 August 2009 Available online 22 November 2009

Representing part-whole relations and effectively using them in domain ontologies and conceptual data models poses multiple challenges. In this paper we face the issue of imposing temporal constraints on part-whole relationships, introducing a way to account for essential and immutable parts (and wholes) in addition to the usual mandatory parts (and wholes). Our approach is based on i) an expli...

This paper examines the role of temporal knowledge in regard to the representation and utilization of constraints within time dependent problem domains. We first consider the representation of constraints whose, interpretations may vary in different temporal regions of the solution space. A representation that organizes constraint variants via the temporal relationships among them is presented ...

The aim of this work is to propose a model for computing the optical flow in a sequence of images. We introduce a new temporal regularizer that is suitable for large displacements. We propose to decouple the spatial and temporal regularizations to avoid an incongruous formulation. For the spatial regularization we use the Nagel–Enkelmann operator and a newly designed temporal regularization. Ou...

This paper addresses the problem of eeciently updating a network of temporal constraints when constraints are removed from or added to an existing network. Such processing tasks are important in many AI applications requiring a temporal reasoning module. First we analyze the relationship between shortest-paths algorithms for directed graphs and arc-consistency techniques. Then we focus on a sub...

In many applications of temporal reasoning we are in­ terested in reasoning incrementally In particular, given a CSP of temporal constrains and a new constraint, we want to maintain certain properties in the extended CSP (e.g., a solution), rather than recomputing them from scratch. The Point Algebra (PA) and the Interval Algebra (IA) are two well-known frameworks for qualitative tem­ poral rea...

This paper considers temporal constraints that can impose a minimum and maximum time distance between the occurrences of two events by specifying the minimum and maximum values in terms of a time granularity. When several constraints using different time granularities are part of the specification of a single problem, a reasonable question is how to convert the constraints in terms of a single ...

We study the performance of some known algorithms for solving the Simple Temporal Problem (STP) and the Temporal Constraint Satisfaction Problem (TCSP). In particular, we empirically compare the Bellman-Ford (BF) algorithm and its incremental version (incBF) by (Cesta & Oddi 1996) to the 4STP of (Xu & Choueiry 2003a). Among the tested algorithms, we show that 4STP is the most efficient for dete...

This paper investigates how centralised, cooperative, multiagent planning problems with concurrent action constraints and heterogeneous agents can be encoded with some minor additions to PDDL, and how such encoded domains can be solved via a translation to temporal planning. Concurrency constraints are encoded on affordances (object-action tuples) and determine the conditions under which a part...