Digraphs

A digraph (or directed graph) has directed edges between two nodes (e.g., a weighted orientation). 

Alternative methods are listed in Table 3.4.6-1 three methods will be discussed in more detail Modular Fault Trees (MET), Go and Digraph. 

Digraph Model and evaluation of components or systems Quantitative, time-dependent multiphased inductive complexity incrc.iM.- rapidly practical only tor simple systems... 

Step 2 - Construct a global digraph model for each accident sequence. 

Step 3 - Partition digraph models into independent subdigraphs and find singleton and doubleton minimum cutsets of accident sequences. 

Alesso, H. P., 1984, On the Relationship of Digraph Matrix Analysis to Petri Net Theory and Fault Trees, LLNL UCRL-90271 Preprint, January. 

Sacks, 1. J. et al., 1983, Systems Interaction Results from the Digraph Matrix Analysis of the Watts Bar Nuclear Power Plant High Pressure Safety Injection Systems, LLNL UCRI..-53467, December. 

This trick of manipulating two or more families of variables simultaneously can be used also with applications of the superposition theorem. This idea seems to have been discovered independently by several workers for an example see [MulI69], where it is used to enumerate a class of regular digraphs. 

To conclude this section, we note quickly a few other asymptotic enumerations. In [PalE70] Palmer found an asymptotic estimate for the number of self-complementary graphs and digraphs. Robinson [RobR76] and Stanley [StaR73] enumerated acyclic digraphs, and obtained the asymptotic estimate... 

C. The asymptotic number of acyclic digraphs. To appear in Combinatorica. 

HarF59b Harary, F. The number of functional digraphs. Math. Annalen. 138 (1959) 203-210. 

HarF67a Harary, F. Enumeration of graphs and digraphs. A seminar in graph theory. (F. Harary, ed.) Holt, Rinehart and Winston, New York (1967) 34-41. 

OttR48 Otter, R. The number of trees. Ann. Math. 49 (1948) 583. PalE70 Palmer, E. M Asymptotic formulas for the number of self-complementary graphs and digraphs. Mathematika 17... 

ReaR63 Read, R. C. On the number of self-complementary graphs and digraphs. J. London Math. Soc. 38 (1963) 99-104. ReaR68 Read, R. C. The use of -functions in combinatorial analysis. Canad. J. Math. 20 (1968) 808-841. 

RobR70 Robinson, R. W. Enumeration of acyclic digraphs. Combinatorial Mathematics and Its Applications (R. C. Bose, et. al. eds.) Univ. of North Carolina, Chapel Hill (1970) 391-399. 

RobR73 Robinson, R. W. Counting labeled acyclic digraphs. New Directions in the Theory of Graphs (F. Harary, ed.)... 

RobR76 Robinson, R. W. Counting unlabeled acyclic digraphs. 

With the view that a KBS interpreter is a method for mapping from input data in the form of intermediate symbolic state descriptions to labels of interest, four families of approaches are described here, each offering inference mechanisms and related knowledge representations that can be used to solve interpretation problems namely, model-based approaches, digraphs, fault trees, and tables. These methods have been heavily used... 

Fig. 29. Digraph. [Drawn from N. A. Wilcox and D. M. Himmelblau, Comput. CHem. Eng. 18, 103 (1994).

Mohindra, S., and Clark, P. A., A distributed fault diagnosis method based on digraph models Steady-state analysis, Comput. Chem. Eng. 17, 193 (1993). 

A. Description and Characterization of Flow Networks 1. Graphs and Digraphs... 

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