A Complete Classification of Tractability in RCC-5

We investigate the computational properties of the spatial algebra RCC-5 which is a restricted version of the RCC framework for spatial reasoning. The satisfiability problem for RCC-5 is known to be NP-complete but not much is known about its approximately four billion subclasses. We provide a complete classification of satisfiability for all these subclasses into polynomial and NP-complete respectively. In the process, we identify all maximal tractable subalgebras which are four in total.Comment: See http://www.jair.org/ for an online appendix and other files accompanying this articl

A Microhistory of Congregational Music-Making in Överselö, Stallarholmen 1754

In 1754 an organ was built in Överselö Church whose purpose was to accompany the congregational singing. My question in this project is to investigate how the accompaniment of the specific congregational singing in Överselö sounded. Sweden adopted its first common hymnal in 1695/97. However, it is not clear from the text of that book how it was used. To reach a higher level of knowledge and understanding of the subject, several components were needed; knowledge from written sources in the field, basic research in materials from the actual church and surrounding areas in Sweden, deepened knowledge about figured bass playing in eighteenth-century Sweden and a prepared experiment for the artistic research. Using artistic research one can make important contributions to the quite unexamined field of knowledge of hymn accompaniment in the eighteenth century. The art of hymn accompaniment is mostly an art of improvisation, which makes it hard to examine using only the tool of musicology. But by learning figured bass playing in the way it was taught in eighteenth-century Sweden and by conducting studies into the way in which hymns were sung one can prepare and evaluate hymn accompaniment using the kind of contextual experiments I have shown in this study. In my study I have deepened the knowledge about interludes, tempo, figured bass in hymn playing and asked questions about who was leading the congregational singing and the role of the organist in the service. The strength of the micro-historical method in this type of study is that you can trace real persons in a specific time and place and their connections to each other. One single micro historic examination does not give the whole picture but since the method “asks large questions in small places” it contributes with new knowledge to the whole: in this case, a clearer picture of how the influences from Germany reached central Sweden and affected the musical traditions here. The results that come out of this kind of project can contribute to the interpretation in several fields of music, such as hymn accompaniment, improvisation and also interpretation of eighteenth-century music

Subsemigroups and congruences for classical transformation semigroups

In this thesis we study and classify all isolated and completely isolatedsubsemigroups and congruences in classical finite transformationsemigroups

Compositionality and the Frame Problem

The problem of compositionally specifying effects of actions has not yet received an appropriate solution, as shown in this paper. A general semanticbased method is proposed, the effect law semantics, which solves this, and has an associated logic for specification of actions. In addition, the semantics completely separates effects of actions from assumptions about inertia (the frame problem), and whether actions have their intended effects or not. This makes it suitable for generalisations, such as handling surprises and actions that may fail

Uniqueness of Scott's Reflexive Domain in P omega

Domains for the pure -calculus, sometimes called reflexive domains, can be constructed in several ways, but the D1 domains found by Scott in 1969 still seem to be the ones with the best properties. The main disadvantage of D1 has been that the construction is considered somewhat artificial. On the other hand, a very concrete domain was found by Scott in 1976, in fact being a subset of P!, the set of subsets of the natural numbers, by means of retracts. The advantage of such a concrete domain is that one may more easily extract its properties, since one can analyse the domain in terms of natural numbers. The main results of this thesis are the following. ffl The reflexive domain in P! is unique, in the sense that it is the only nontrival solution to the retract equation d = dffi!d. ffl The P! domain is isomorphic to one of the D1 models. This implies that we may adopt results about the D1 domains for the P! domain. ffl The domain possesses no second least elements. ffl An algorithm..