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A pointing device plays an important role in human-computer interaction. The computer mouse is a convenient device for both pointing and steering. The literature related to the effect of mouse gain on steering tasks is scarce. An experiment was conducted with 10 participants and each participant was asked to traverse a constrained path using a computer mouse. There were three levels of gain approximately equal to 2.3, 10, and 15. The experiment had 11 levels of difficulty (D/P) based on path width (P) and path length (D) and three trials for each combination of D and P. Performance was evaluated using movement time taken to traverse the path. The results showed that movement time is minimized, in feedback-controlled steering tasks, at a gain of around nine.

We prove that every n-vertex graph G with path-width pw(G) has a three-dimensional straight-line grid drawing with O(pw(G)2?n) volume. Thus for graphs with bounded path-width the volume is O(n), and it follows that for graphs with bounded tree-width, such as series-parallel graphs, the volume is O(n log2 n). No better bound than O(n2) was previously known for drawings of series-parallel graphs. For planar graphs we obtain three-dimensional drawings with O(n2) volume and O(?n) aspect ratio, whereas all previous constructions with O(n2) volume have ?(n) aspect ratio.

The problem to decide whether the tree-width of a comparability graph is less than k is NP-complete, if k is part of the input. We prove that the tree-width of comparability graphs of interval orders can be determined in linear time and that it equals the path-width of the graph. Our proof is constructive, i.e., we give an explicit path decomposition of the graph.