Completion-based algorithms can be employed for computing the least common subsumer of two concepts up to a given role-depth, in extensions of the lightweight DL EL. This approach has been applied also to the probabilistic DL Prob-EL, which is variant of EL with subjective probabilities. In this paper we extend the completion-based lcscomputation algorithm to nominals, yielding a procedure for ...

We consider the evolution of a population of fixed size with no selection. The number of generations G to reach the first common ancestor evolves in time. This evolution can be described by a simple Markov process which allows one to calculate several characteristics of the time dependence of G. We also study how G is correlated to the genetic diversity.

By a theorem of Dobrow and Smythe, the depth of the kth node in very simple families of increasing trees (which includes, among others, binary increasing trees, recursive trees and plane ordered recursive trees) follows the same distribution as the number of edges of the form j−(j+1) with j < k. In this short note, we present a simple bijective proof of this fact, which also shows that the resu...

Methods for computing the least common subsumer (lcs) are usually restricted to rather inexpressive DLs whereas existing knowledge bases are written in very expressive DLs. In order to allow the user to re-use concepts defined in such terminologies and still support the definition of new concepts by computing the lcs, we extend the notion of the lcs of concept descriptions to the notion of the ...

Before embarking into the technicalities of the different algorithms for LCA, let us first agree on the terminology that we will be using throughout this article. Let there be a rooted tree T(E,V). A node x ∈ T is called an ancestor of a node y ∈ T if the path from the root of T to y goes through x. Also, a node v ∈ T is called to be a common ancestor of x and y if it is an ancestor of both x a...

In particular, we are allowed to preprocess the texts in order to be able to answer the query faster. Our preprocessing choice was the use of a single suffix tree, in which all the suffixes of all the texts appear, each suffix ending with a distinct symbol that determines the text in which the suffix appears. In order to answer the query we reduced the problem to range-min queries, which in tur...

Least Common Ancestor Networks (LCANs) are introduced and shown to be a class of networks that include fat-trees, baseline networks, SW-banyans and the router networks of the TRAC 1.1 and 2.0, and the CM-5. Some LCAN properties are stated and the permutation routing capabilities of an important subclass are analyzed. Simulation results for three permutation classes verify the accuracy of an ite...