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SweConsNet Workshop 2013

The 12th Workshop of the Network of Sweden-based researchers and practitioners of Constraint programming

SweConsNet is the Network for Sweden-based researchers and practitioners of Constraint programming.

Following the previous successful workshops, we would like to announce the 12th SweConsNet workshop, which will take place in Lund, Sweden on May 27th 2013. The purpose of this workshop is to learn about ongoing research in constraint programming, as well as existing projects and products. We will also discuss the further development of the network, such as a possible widening to other Nordic countries.

The workshop is open to everybody interested in the theory and practice of constraint programming, whether based in Sweden or elsewhere. The scope of the workshop spans all areas of Constraint Programming, and is open to presentations and discussions addressing topics related to both theory and application.

Please forward a link of this page to people who might be interested but are not yet on the SweConsNet mailing list. They can subscribe to it by sending a message to Justin.Pearson [at] it.uu.se.

We hope for your participation, and highly encourage you to submit a proposal for a presentation of your ongoing work, recent results, or of a relevant discussion topic. There are no paper submissions, reviews, or proceedings, hence recent conference/journal papers may also be presented.

The workshop does not have a registration fee. Registration is closed


09.30Registration and coffee

Jean-Noël Monette (Uppsala University)
Towards solver-independent propagators

We present an extension to indexicals to describe propagators for global constraints. The resulting language is compiled into actual propagators for different solvers, and is solver-independent. In addition, we show how this high-level description eases the proof of propagator properties, such as correctness and monotonicity. Experimental results show that propagators compiled from their indexical descriptions are sometimes not significantly slower than built-in propagators of Gecode. Therefore, our language can be used for the rapid prototyping of new global constraints


Mats Carlsson (SICS) (joint work with Nicolas Beldiceanu & Aranud Letort)
Scalable Scheduling Constraints

The topic of this talk is synchronized sweep-based filtering algorithms for resource and precedence constraints that are common in scheduling problems.  We first describe a sweep-based implementation of the time-tabling method for "cumulative". Step by step, we then extend this algorithm to handle colored resources, multiple resources, and precedences.  We also derive from the filtering algorithm a greedy assignment algorithm, which is useful for very large scale problems where normal tree search would run out of memory.


Mehmet A. Arslan (LTH)
Instruction Selection and Scheduling for DSP Kernels on Custom Architectures

As custom architectures become more and more common for DSP applications, instruction selection and scheduling for such applications and architectures become important topics. In this paper, we explore the effects of defining the problem of finding an optimal instruction selection and scheduling as a constraint satisfaction problem (CSP). We incorporate methods based on sub-graph isomorphism and global constraints designed for scheduling. We experiment using several media applications on a custom architecture, a generic VLIW architecture and a RISC architecture, all three with several cores. Our results show that defining the problem with constraints gives flexibility in modeling, while state-of-the-art constraint solvers enable optimal solutions for large problems, hinting a new method for code generation. 

11.30Gabriel Hjort Blindell (KTH)
Constraint-based Instruction Selection

Contemporary compilers struggle with irregular and complex target architectures as the traditional heuristics for code generation break down when certain assumptions about the hardware no longer hold. This is especially true for embedded systems and DSPs. We present a hybrid approach to constraint-based instruction selection where the strengths of the traditional techniques are used for pattern matching and the flexibility of constraint programming is used for optimal pattern selection. Instruction selection is one of the core tasks for code generation, the others being instruction scheduling and register allocation.

Kim-Anh Tran (SICS)
Investigation of Implied Constraints in a Constraint-Based Compiler Back-end

Adding implied constraints addressing register allocation and instruction scheduling to the constraint model of a compiler back-end can be crucial to the performance of the code generator. In the hope of cutting down the search effort, implied constraints are investigated, implemented and evaluated. The talk will cover current findings of a master thesis on a set of implied constraints and give an insight into their actual impact on the code generation problem.


Håkan Kjellerstrand
What I like about Constraint Programming

This is a presentation about fascinating features in Constraint Programming: those I personally find very appealing and/or unique (e.g. compared to other programming paradigms/systems), especially regarding the modeling aspect.


Björn Regnell (LTH)
A Scala DSL for Constraint-based Requirement Engeineering

Software Requirements Engineering (RE) includes the challenging activities of release planning and prioritization, which both are suitable to be tackled by constraint solving. However, there is a need for integrating the representation of software requirements with the representation of constraints in a way that is easy to use by practitioners. This talk aims to interactively discuss what types of constraints are essential in this domain and present and invite feedback on a prototype tool that provides a Scala-internal DSL for Constraint-based RE, wrapping the JaCoP solver.

15.00Coffee break

Krzysztof Kuchcinski (LTH) 
Mapping Streaming Application into MPSoc

The topic of this presentation is mapping, path selection and router configuration for streaming applications (such as MPEG) running on multi-processor platforms (MPSoC) with guaranteed service interconnects. State of the art approaches in this area largely rely on greedy heuristics. Our approach is based on a constraint programming formulation that combines several of the classical sequential steps, with the potential of finding optimal solutions with respect to resource usage, while keeping bandwidth requirements. 

16.10Workshop closure
Sidansvarig: Jonas.Wisbrant@cs.lth.se | 2015-11-06

Short Facts

When: May 27, 2013

Where: E:1406, Ole Römers väg 3, Lund

Organizer: Prof. Krzysztof Kuchcinski, Department of Computer ScienceLTHLund University.

Register is closed!

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