منابع مشابه
Directed Graph Embeddings
Definitions of graph embeddings and graph minors for directed graphs are introduced. For the class of 2-terminal directed acyclic graphs (TDAGs) the definitions coincide, and the class is closed under both operations. The usefulness of the directed embedding operation is demonstrated be characterizing all TDAGs with parallel-width at most $k$, which generalizes earlier characterizations of seri...
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We study the problem of characterizing the directed graphs with an upward straightline embedding into every point set in general or in convex position. We solve two questions posed by Binucci et al. [Computational Geometry: Theory and Applications, 2010 ]. Namely, we prove that the classes of directed graphs with an upward straightline embedding into every point set in convex position and with ...
متن کاملRandom Iteration Algorithm for Graph-Directed Sets
A random iteration algorithm for graph-directed sets is defined and discussed. Similarly to the Barnsley-Elton’s theorem, it is shown that almost all sequences obtained by this algorithm reflect a probability measure which is invariant with respect to the system of contractions with probabilities.
متن کاملUpward Straight-Line Embeddings of Directed Graphs into Point Sets
In this paper we consider the problem of characterizing the directed graphs that admit an upward straight-line embedding into every point set in convex or in general position. In particular, we show that no biconnected directed graph admits an upward straight-line embedding into every point set in convex position, and we provide a characterization of the Hamiltonian directed graphs that admit u...
متن کاملDirected prime graph of non-commutative ring
Prime graph of a ring R is a graph whose vertex set is the whole set R any any two elements $x$ and $y$ of $R$ are adjacent in the graph if and only if $xRy = 0$ or $yRx = 0$. Prime graph of a ring is denoted by $PG(R)$. Directed prime graphs for non-commutative rings and connectivity in the graph are studied in the present paper. The diameter and girth of this graph are also studied in the pa...
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ژورنال
عنوان ژورنال: Annales Academiae Scientiarum Fennicae Mathematica
سال: 2016
ISSN: 1239-629X,1798-2383
DOI: 10.5186/aasfm.2016.4153