Mathematical evolution in discrete networks

This paper provides a mathematical explanation for the phenomenon of \triadic closure" so often seen in social networks. It appears to be a natural consequence when network change is constrained to be continuous. The concept of chordless cycles in the network's \irreducible spine" is used in the analysis of the network's dynamic behavior. A surprising result is that as networks undergo random, but continuous, perturbations they tend to become more structured and less chaotic

TREETRAN - A Fortran IV subroutine package for manipulation of rooted trees

Fortran IV subroutine package for manipulation of rooted trees - Treetra

Pattern recognition- iv. sequential operations in digital picture processing

Sequential approach to digital picture processin

Closure and Causality

We present a model of causality which is defined by the intersection of two distinct closure systems, ${cal I}$ and ${cal T}$. Next we present empirical evidence to demonstrate that this model has practical validity by examining computer trace data to reveal causal dependencies between individual code modules. From over 498,000 events in the transaction manager of an open source system we tease out 66 apparent causal dependencies. Finally, we explore how to mathematically model the transformation of a causal topology resulting from unforlding events

Pattern recognition. v- samp - a computer program for estimating surface area from contour maps

Fortran computer program for computing linear approximation of surface area for any given portion of digitized contour ma

Convexity in directed graphs

AbstractIn this paper the concept of convexity in directed graphs is described. It is shown that the set of convex subgraphs of a directed graph G partially ordered by inclusion forms a complete, semimodular, A-regular lattice, denoted ℒG. The lattice theoretic properties of the convex subgraph lattice lead to inferences about the path structure of the original graph G. In particular, a graph factorization theorem is developed. In Section 4, several graph homomorphism concepts are investigated in relation to the preservation of convexity properties. Finally we characterize an interesting class of locally convex directed graphs

Recent Progress in Iridium-Catalyzed Enantioselective Hydrogenation: Tetrasubstituted Olefins and Polyenes

Iridium-catalyzed enantioselective hydrogenation has become the method of choice to convert prochiral unfunctionalized olefins to optically active compounds. Recently, we reported on applications giving access to more than one stereocenter in a single hydrogenation step. In this account we present recent developments in the hydrogenation of tetrasubstituted unfunctionalized olefins and isoprenoid polyenes, which allow the generation of two stereocenters in a single hydrogenation step

Warthin-Tumor mit Karzinom: Maligne Transformation oder Metastase?

Zusammenfassung: Wir berichten über einen ungewöhnlichen Fall eines langjährig klinisch diagnostizierten Warthin-Tumors (WT) mit plötzlicher Größenzunahme und nachfolgender Resektion. Histologisch konnte der WT bestätigt werden, zeigte jedoch zusätzlich diffuse Infiltrate eines dissolut wachsenden Adenokarzinoms. Unter der Annahme eines maligne transformierten WT wurden radiologische Staging-Untersuchungen angeschlossen, mit deren Hilfe ein metastasierendes Mammakarzinom mit identischer Morphologie zu den WT-Infiltraten entdeckt wurde. Die seltene Diagnose eines maligne transformierten WT erfordert daher immer den Ausschluss eines metastasierten Tumorleiden