$\parbox{7cm}{ {\Huge\bf SEMINARIUM}}$
Matematyka Dyskretna
(prowadzone przez M.Woźniaka)

UWAGA!!!  UWAGA!!!  UWAGA!!!

Spotkanie nadzwyczajne!, termin wyjątkowy!

W środę, 2 czerwca 2004 roku, o godzinie 15:00

w sali 304, łącznik A-3-A-4, A G H

Zdenek RYJÁČEK

(Pilzno, Czechy)

wygłosi referat pod tytułem:

Stability of graph properties

A class of graph ${\cal C}$ is said to be stable under a closure operation cl if $G\in {\cal C}$ implies ${\rm cl} (G) \in {\cal C}$. Let ${\cal C}$ be a stable class and ${\cal P}$ a property. We say that ${\cal P}$ is stable in ${\cal C}$ under cl, if, for any $G\in {\cal C}$, $G$ has ${\cal P}$ if and only if ${\rm cl} (G)$ has ${\cal P}$. Similarly, a graph invariant $\pi$ is stable in ${\cal C}$ under cl if $\pi (G) = \pi ({\rm cl} (G))$ for any $G\in {\cal C}$. Proving a stability result is usually the first step in applying closure technique to a specific problem. We survey known results on stability of graph properties and invariants under the closure operations based on local completions and on subgraph contractions. Applications of these results and some open questions will be discussed

Serdecznie zapraszamy wszystkich chętnych !