The forces promoting and constraining speciation are often studied in theoretical models because the process is hard to observe, replicate, and manipulate in real organisms. Most models analyzed to date include pre-defined functions influencing fitness, leaving open the question of how speciation might proceed without these built-in determinants. To consider the process of speciation without pr...

One of the more dramatic life histories in the natural world is that characterized by a single, massive, fatal reproductive episode ('semelparity'). A wealth of increasingly sophisticated theoretical models on differential life history evolution have been produced over the last two decades. In recent years, empirical studies of the ecology of semelparous plants (and their iteroparous relatives)...

The purpose of this research is the identification of a paradigm which fixes the basic concepts and the type of logical relationships between them, whereby direct, govern and evaluate choises on new technologies. The contribution is based on the assumption that the complexity of knowledge is correlated with the complexity of the learning environment. From the existence of this correlation will ...

When Axel Thue wrote these lines in the introduction to his 1912 paper on squarefree words, he certainly did not feel as a theoretical computer scientist. During the past seventy years, there was an increasing interest in squarefree words and more generally in repetitions in words. However, A. Thue's sentence seems still to hold : in some sense, he said that there is no reason to study squarefr...

385 EIsevier Note Îï the distributional complexity of disjointness Abstract Razborov, À.À., Îï the distributional complexity of disjointness, Theoretical Computer ScienCe 106 (1992) 385-390. We prove that the distributional communication complexity of the predicate "disjointness" with respect to à very simple measure îï inputs is Ùï).

It is well known that for the case of a countable partial order, the ideal completion and the chain completion coincide. We investigate the boundary at which the chain and ideal completion do not coincide. We show in particular that the ideal completion is not sequentially adequate; that is it is not possible in general to simply replace the ideal completion with a completion based on sequences...

Structures exhibiting strong comprehension properties have been utilized in different fields of Mathematical Logic and Theoretical Computer Science. Although the techniques employed and the intended applications are quite different, these structures are essentially alike. Starting from a general definition of Hyperuniverse, we present here a comprehensive framework for investigating these struc...