Reducing the clique and chromatic number via edge contractions and vertex deletions.

We consider the following problem: can a certain graph parameter of some given graph G be reduced by at least d, for some integer d, via at most k graph operations from some specified set S, for some given integer k? As graph parameters we take the chromatic number and the clique number. We let the set S consist of either an edge contraction or a vertex deletion. As all these problems are NP-complete for general graphs even if d is fixed, we restrict the input graph G to some special graph class. We continue a line of research that considers these problems for subclasses of perfect graphs, but our main results are full classifications, from a computational complexity point of view, for graph classes characterized by forbidding a single induced connected subgraph H

Comparing the lifestyles and environmental perceptions of rural and urban children: a case study in Turkey

This study aims to compare lifestyles and environmental perceptions of urban and rural children. Ninety-two students completed a questionnaire and were given two means (drawing or wring) to express their thoughts regarding (1) the activity and play areas, (2) their neighborhood and (3) their city. The results showed higher levels of parental supervision and restrictions on the independent mobility of the urban children in outdoor areas. This and other differences regarding the life styles are reflected in the children's drawings of various settings. The results have applied value for planners and urban designers, and additional research is currently underway