Bacteria Can Be Predators, Too

Testing Can Be Formal, Too

The paper presents a theory of program testing based on formal specifications. The formal semantics of the specifications is the basis for a notion of an exhaustive test set. Under some minimal hypotheses on the program under test, the success of this test set is equivalent to the satisfaction of the specification. The selection of a finite subset of the exhaustive test set can be seen as the i...

Can We Be Too Careful?

Can there be more predators than prey?

One of the few general “theorems” of ecology is the statement that in a given habitat there can be no more species present than the number of limiting resources. Our aim is to examine several of the versions of this “theorem” present in the literature, to compare them and to consider the underlying assumptions and definitions so as to decide to what ecological situations the theorem is applicab...

Too Much Information Can Be Too Much for Learning Eciently

In designing learning algorithms it seems quite reasonable to construct them in a way such that all data the algorithm already has obtained are correctly and completely re ected in the description the algorithm outputs on these data. However, this approach may totally fail, i.e., it may lead to the unsolvability of the learning problem, or it may exclude any e cient solution of it. In particula...

Can frequent hemodialysis be too frequent?

Many nephrologists believe that more hemodialysis, whether in the form of longer treatments, more frequent treatments, or both, is better than less. Emerging evidence largely supports this view, with most, although not all studies, showing biochemical, cardiovascular, quality of life, or survival benefits with short daily or slow nocturnal hemodialysis. Much of the focus of studies thus far has...