A practical method is presented for eliminating unnecessary database operations that often arise from poorly posed natural language queries. This subsystem consists mainly of a knowledge-base whose rules are semantic constraints of the database. The inference procedure's actions are, unlike that of similar inference engines, strictly controlled by the structure of the query. Because of this it is easy to implement and it is relatively fast. It is believed that this subsystem represents a practical incremental improvement that can be made to any relational database front end, not just those that must cope with natural language queries. The procedure also has value as part of a practical semantic query optimizer.>

Abstract I agree that probability in some, possibly disguised, form is a necessary component of practical inference. Our goal, therefore, must be to find how to make probability practical. Normatively motivated thinking (which includes textbook Bayesianism) is, however, mute on two topics that are crucial to practicality: the choice of a limited but useful set of initial hypotheses and the choice of decision rules. The best way of reducing the computational demands of probability is to use the smallest and simplest set of hypotheses, and the crudest decision rules that are compatible with your application's goals. Learning how to make these choices is an empirical, not a normative, endeavour.

Using a simple finite degree interconnection network among n processors and a straightforward randomized algorithm for packet delivery, it is possible to deliver a set of n packets travelling to unique targets from unique sources in 0(log n) expected time. The expected delivery time is in other words the depth of the interconnection graph. The b -way shufile networks are examples of such.

The main results in this paper demonstrate that there exist pairs of integers 〈E, D〉 (for "area Expansion" and "edge Dilation," respectively) such that any n-vertex rectangular grid can be embedded into a square grid having at most En vertices, in such a way that images in the square grid of vertices that are adjacent in the rectangular grid are at most distance D apart. Several techniques for "squaring"-up rectangular grids are presented; sample values for the parameter-pair 〈E, D〉 are: 〈E = 1.2, D = 15〉, 〈E = 1.45, D = 9〉, 〈E = 1.8, D = 3〉. Note that these values of E and D hold for all rectangular grids, independent of number of vertices. The quest for these results was motivated by the question of whether or not one could automatically "square up" circuit layouts having aspect ratios very far from unity, without compromising the efficiency of the layout (in terms of area and length of the longest run of wire). The results reported here yield an affirmative answer to this question, at least in an idealized setting. One corollary of the embeddings presented here is that the side-2n½ square "king's-move" grid contains as a subgraph every n-vertex rectangular grid. Another way to think of this result is that this embellished grid can be "programmed" or "personalized," by setting switches, to represent any n-vertex rectangular grid.