𝔖 Bobbio Scriptorium
✦   LIBER   ✦

A contraction theorem for abstract graphs

✍ Scribed by G. A. Dirac

Publisher
Springer
Year
1961
Tongue
English
Weight
224 KB
Volume
144
Category
Article
ISSN
0025-5831

No coin nor oath required. For personal study only.

📜 SIMILAR VOLUMES

Contraction–Deletion Invariants for Grap
Contraction–Deletion Invariants for Graphs
✍ Béla Bollobás; Luke Pebody; Oliver Riordan 📂 Article 📅 2000 🏛 Elsevier Science 🌐 English ⚖ 192 KB

We consider generalizations of the Tutte polynomial on multigraphs obtained by keeping the main recurrence relation T(G)=T(GÂe)+T(G&e) for e # E(G) neither a bridge nor a loop and dropping the relations for bridges and loops. Our first aim is to find the universal invariant satisfying these conditio

A duality theorem for graph embeddings
A duality theorem for graph embeddings
✍ Brad Jackson; T. D. Parsons; Tomaž Pisanski 📂 Article 📅 1981 🏛 John Wiley and Sons 🌐 English ⚖ 918 KB

## Abstract A generalized type of graph covering, called a “Wrapped quasicovering” (wqc) is defined. If __K, L__ are graphs dually embedded in an orientable surface __S__, then we may lift these embeddings to embeddings of dual graphs K̃,L̃ in orientable surfaces S̃, such that S̃ are branched cover

A fixed cube theorem for median graphs
A fixed cube theorem for median graphs
✍ Hans-Jürgen Bandelt; Marcel van de Vel 📂 Article 📅 1987 🏛 Elsevier Science 🌐 English ⚖ 513 KB

The following result is proven: every edge-preserving self-map of a median graph leaves a cube invariant. This extends a fixed edge theorem for trees and parallels a result on invariant simplices in contractible graphs.