Authors 
Title 
Status, Abstract 

Gunther Schmidt 
Implication Structures.pdf .bib 
Presented at RelMiCS 8, Relational Methods in Computer ScienceFebruary 2226, 2005, St. Catharines, Ontario, Canada pages 227237 of Participants Proceedings edited by Ivo Düntsch and Michael Winter, Brock University 

University of the Federal Armed Forces Munich 85577 Neubiberg, Germany Gunther.Schmidt@Unibw.DE 

This is a case study using the proposed relational multilevel reference language
in order to deal with the interesting logical concept of implication structures,
developed already in
Gunther Schmidt and Thomas Ströhlein In the course of these investigations, the timetable problem is introduced on a pointfree relational level by reworking the papers mentioned before, thus providing an important example of an implication structure. An implication structure is given when a choice of a subset has to be made from a set of items where an item chosen may imply/forbid some others to be chosen. Also not choosing an item may enforce another one to be chosen. The problem is related to satisfiability. It is, thus, NPcomplete, and will normally not admit an efficient algorithm. When studying the implication structure mentioned from the relationalgebraic side, this may result in theoretically sound heuristical approaches. 