Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

In the context of object-oriented systems, algorithms for building class hierarchies are currently receiving much attention. We present here a characterization of several global algorithms. A global algorithm is one which starts with only the set of classes (provided with all their properties) and directly builds the hierarchy. The algorithms scrutinized were developped each in a different framework. In this survey, they are explained in a single framework, which takes advantage of a substructure of the Galois lattice associated with the binary relation mapping the classes to their properties. Their characterization allows to figure the results of the algorithms without running them in simple cases. This study once again highlights the Galois lattice as a main and intuitive model for class hierarchies.

1. The results from two studies are reported of the effects on mental performance of omitting breakfast. The objective of the first study was to compare the performances of schoolchildren who habitually ate or did not eat breakfast. In the second study the effectsof omitting breakfast by those accustomed to eating the morning meal were investigated.

2. Mental performance was assessed by two short-term memory tests (a simple cancellation test in which paired letters were marked on a page of random letters) and a memory-search test in which tines containing a group of specified fetters were marked, a series of numerical additions, and an attention-demanding test (in which specified statements had to be verified).

3. Neither study revealed differences attributable to the omission or consumption of breakfast.