A constraint hierarchies approach to geometric constraints on sketches

International audienceWe propose an approach that uses preferences on the constraints in order to deal with over-constrained geometric constraint problems. This approach employs constraint hierarchies, a paradigm that has close relations with the traditional graph-based approaches used in geometric constraint solving. We also remark that any geometric constraint problem defined by imposing relations on a sketch becomes overconstrained as soon as the sketch is imposed as a weak constraint representing the designers intents. As a result our method appears very appropriate in CAD/CAM tools

Solving Finite Domain Constraint Hierarchies by Local Consistency and Tree Search

We provide a reformulation of the constraint hierarchies (CHs) framework based on the notion of error indicators. Adapting the generalized view of local consistency in semiring-based constraint satisfaction problems (SCSPs), we define constraint hierarchy k -consistency (CH-k-C) and give a CH-2-C enforcement algorithm. We demonstrate how the CH-2-C algorithm can be seamlessly integrated into the ordinary branch-and-bound algorithm to make it a finite domain CH solver. Experimentation confirms the efficiency and robustness of our proposed solver prototype. Unlike other finite domain CH solvers, our proposed method works for both local and global comparators. In addition, our solver can support arbitrary error functions

In search of grammaticalization in synchronic dialect data: General extenders in north-east England

In this paper, we draw on a socially stratified corpus of dialect data collected in north-east England to test recent proposals that grammaticalization processes are implicated in the synchronic variability of general extenders (GEs), i.e., phrase- or clause-final constructions such as and that and or something. Combining theoretical insights from the framework of grammaticalization with the empirical methods of variationist sociolinguistics, we operationalize key diagnostics of grammaticalization (syntagmatic length, decategorialization, semantic-pragmatic change) as independent factor groups in the quantitative analysis of GE variability. While multivariate analyses reveal rapid changes in apparent time to the social conditioning of some GE variants in our data, they do not reveal any evidence of systematic changes in the linguistic conditioning of variants in apparent time that would confirm an interpretation of ongoing grammaticalization. These results lead us to questio

Transformations between HCLP and PCSP

We present a general methodology for transforming between HCLP and PCSP in both directions. HCLP and PCSP each have advantages when modelling problems, and each have advantages when implementing models and solving them. Using the work presented in this paper, the appropriate paradigm can be used for each of these steps, with a meaning-preserving transformation in between if necessary

Solving finite domain constraint hierarchies by local consistency and tree search.

by Hui Kau Cheung Henry.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.Includes bibliographical references (leaves 107-112).Abstracts in English and Chinese.Abstract --- p.iiAcknowledgments --- p.iiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.2 --- Organizations of the Thesis --- p.2Chapter 2 --- Background --- p.4Chapter 2.1 --- Constraint Satisfaction Problems --- p.4Chapter 2.1.1 --- Local Consistency Algorithm --- p.5Chapter 2.1.2 --- Backtracking Solver --- p.8Chapter 2.1.3 --- The Branch-and-Bound Algorithm --- p.10Chapter 2.2 --- Over-constrained Problems --- p.14Chapter 2.2.1 --- Weighted Constraint Satisfaction Problems --- p.15Chapter 2.2.2 --- Possibilistic Constraint Satisfaction Problems --- p.15Chapter 2.2.3 --- Fuzzy Constraint Satisfaction Problems --- p.16Chapter 2.2.4 --- Partial Constraint Satisfaction Problems --- p.17Chapter 2.2.5 --- Semiring-Based Constraint Satisfaction Problems --- p.18Chapter 2.2.6 --- Valued Constraint Satisfaction Problems --- p.22Chapter 2.3 --- The Theory of Constraint Hierarchies --- p.23Chapter 2.4 --- Related Work --- p.26Chapter 2.4.1 --- An Incremental Hierarchical Constraint Solver --- p.28Chapter 2.4.2 --- Transforming Constraint Hierarchies into Ordinary Con- straint System --- p.29Chapter 2.4.3 --- The SCSP Framework --- p.30Chapter 2.4.4 --- The DeltaStar Algorithm --- p.32Chapter 2.4.5 --- A Plug-In Architecture of Constraint Hierarchy Solvers --- p.34Chapter 3 --- Local Consistency in Constraint Hierarchies --- p.36Chapter 3.1 --- A Reformulation of Constraint Hierarchies --- p.37Chapter 3.1.1 --- Error Indicators --- p.37Chapter 3.1.2 --- A Reformulation of Comparators --- p.38Chapter 3.1.3 --- A Reformulation of Solution Set --- p.40Chapter 3.2 --- Local Consistency in Classical CSPs --- p.41Chapter 3.3 --- Local Consistency in SCSPs --- p.42Chapter 3.4 --- Local Consistency in CHs --- p.46Chapter 3.4.1 --- The Operations of Error Indicator --- p.47Chapter 3.4.2 --- Constraint Hierarchy k-Consistency --- p.49Chapter 3.4.3 --- A Comparsion between CHAC and PAC --- p.50Chapter 3.4.4 --- The CHAC Algorithm --- p.52Chapter 3.4.5 --- Time and Space Complexities of the CHAC Algorithm --- p.53Chapter 3.4.6 --- Correctness of the CHAC Algorithm --- p.56Chapter 4 --- A Consistency-Based Finite Domain Constraint Hierarchy Solver --- p.59Chapter 4.1 --- The Branch-and-Bound CHAC Solver --- p.59Chapter 4.2 --- Correctness of the Branch-and-Bound CHAC Solver --- p.61Chapter 4.3 --- An Example Execution Trace --- p.64Chapter 4.4 --- Experiments and Results --- p.66Chapter 4.4.1 --- Experimental Setup --- p.68Chapter 4.4.2 --- The First Experiment --- p.71Chapter 4.4.3 --- The Second Experiment --- p.94Chapter 5 --- Concluding Remarks --- p.103Chapter 5.1 --- Summary and Contributions --- p.103Chapter 5.2 --- Future Work --- p.104Bibliography --- p.10

Using graphical style and visibility constraints for a meaningful layout in visual programming interfaces

In the expanding field of visual applications, layout design and graphical editing tasks are crucial points. In this paper, we address the incorporation of AI aspects in the visual software design process and the automatic layout and beautification of informational graphics such as visual programs and chart diagrams. Since layout in dynamic settings frequently requires a direct manipulation responsiveness, an incremental redesign of the generated visual material is necessary. Following our previous work on constraint-based multimodal design, we show how powerful constraint processing techniques, such as constraint hierarchies and dynamic constraint satisfaction, can be applied to visual programming environments in order to maintain graphical style and consistency for a meaningful layout. We describe InLay, a system for constraint-based presenting and editing visual programs. Finally, we will have a short look at some extensions with regard to advanced interaction and visualization techniques

Dealing with Web service QoS factors using constraint hierarchy

Functionality and non-functional properties are two critical factors in web service technology, but non-functional properties (quality factors) are often ignored. Usually, these are articulated as statements of objectives, as opposed to prepositional assertions. A key challenge in dealing with objectives is that there is no obvious means to decide when they are satisfied. In effect, these objectives are never fu lly satisfied, but satisficed to varying degrees. Alternative design decisions need to trade-off varying degrees of satisfaction of potentially mutually contradictory non-functional requirements. In some circumstances, non-Junctional properties are crucial; they do affect the design decision. Upon a request, there are a range o f web services that might provide the required functionality, so the web service selection can only be done based on their Quality of Service (QoS). Therefore, a quality-based web service model is in high demand. The key contribution of this paper is the use of the hierarchical constraint logic programming framework [9, 10] in dealing with quality factors. We show how quality factors can be formulated as soft constraints and how the machinery associated with constraint hierarchies can be used to evaluate the web services