Short proofs for interval digraphs
โ Scribed by Douglas B. West
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 327 KB
- Volume
- 178
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
โฆ Synopsis
We give short proofs of the adjacency matrix characterizations of interval digraphs and unit interval digraphs.
๐ SIMILAR VOLUMES
A short proof is given of the fact that every graph has an interval representation of depth 2 in which each vertex u is represented by at most &f(u) + 11 intervals, except for an arbitrarily specified vertex w that appears left-most in the representation and is represented by at most [&d(w) + 1)1 in
## Electric Adhesion of Metal Contaets.--A. Stroh has experimented upon tile ~'~dhesion of two metals in mutual contact during the passage of an electric current. Tile adhesion is manifested most strikinly when the metals touch upon two edges crosswise; it changes with the nature of the metal. S~r
In the minimum sum coloring problem we have to assign positive integers to the vertices of a graph in such a way that neighbors receive different numbers and the sum of the numbers is minimized. Szkalicki has shown that minimum sum coloring is NP-hard for interval graphs. Here we present a simpler p