Abstract
Naj bo ▫$I_G(x,y)$▫ interval najkrajših ▫$x,y$▫-poti in ▫$J_G(x,y)$▫ interval induciranih ▫$x,y$▫-poti v povezanem grafu ▫$G$▫. Obravnavani so naslednji trije aksiomi vmesnosti za množico ▫$V$▫ in ▫$R: V \times V \rightarrow 2^V$▫: (i) ▫$x \in R(u,y), y \in R(x,v), x \neq y, |R(u,v)|>2 \Rightarrow x \in R(u,v)$▫; (ii) ▫$x \in R(u,v) \Rightarrow R(u,x) \cap R(x,v) = \{x\}$▫; (iii) ▫$x \in R(u,y), y \in R(x,v), x \neq y, \Rightarrow x \in R(u,v)$▫. Karakteriziramo razred grafov, za katere ▫$I_G$▫ izpolnjuje (i), razred grafov, za katere ▫$J_G$▫ izpolnjuje (ii) in razred grafov, kjer oba ▫$I_G$▫ in ▫$J_G$▫ izpolnjujeta (iii). Karakterizacije so podane z prepovedanimi induciranimi podgrafi. Izkaže se, da je razred grafov, kjer ▫$I_G$▫ izpolnjuje (i), pravi podrazred razdaljno dednih grafov in da je razred, kjer ▫$J_G$▫ izpolnjuje (ii), pravi nadrazred razdaljno dednih grafov. Podani sta tudi aksiomatični karakterizaciji tetivnih in ptolomejskih grafov.
Keywords
matematika;teorija grafov;prepovedani podgrafi;inducirana pot;intervalna funkcija;aksiomi vmesnosti;tetivni grafi;razdaljno dedni grafi;mathematics;graph theory;forbidden subgraphs;induced path;interval function;betweenness axioms;chordal graphs;distance hereditary graphs;
Data
Language: |
English |
Year of publishing: |
2013 |
Typology: |
1.01 - Original Scientific Article |
Organization: |
UM FS - Faculty of Mechanical Engineering |
UDC: |
519.17 |
COBISS: |
16567385
|
ISSN: |
0012-365X |
Views: |
41 |
Downloads: |
34 |
Average score: |
0 (0 votes) |
Metadata: |
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Other data
Secondary language: |
Slovenian |
Secondary title: |
Karakterizacija prepovedanih podgrafov nekaterih grafov z uporabo aksiomov vmesnosti |
Secondary abstract: |
Let ▫$I_G(x,y)$▫ and ▫$J_G(x,y)$▫ be the geodesic and induced path interval between ▫$x$▫ and ▫$y$▫ in a connected graph ▫$G$▫, respectively. The following three betweenness axioms are considered for a set ▫$V$▫ and ▫$R: V \times V \rightarrow 2^V$▫: (i) ▫$x \in R(u,y), y \in R(x,v), x \neq y, |R(u,v)|>2 \Rightarrow x \in R(u,v)$▫; (ii) ▫$x \in R(u,v) \Rightarrow R(u,x) \cap R(x,v)= \{x\}$▫; (iii)▫$x \in R(u,y), y \in R(x,v), x \neq y, \Rightarrow x \in R(u,v)$▫. We characterize the class of graphs for which ▫$I_G$▫ satisfies (i), and the class for which ▫$J_G$▫ satisfies (ii) and the class for which ▫$I_G$▫ or ▫$J_G$▫ satisfies (iii). The characterization is given by forbidden induced subgraphs. It turns out that the class of graphs for which ▫$I_G$▫ satisfies (i) is a proper subclass of distance hereditary graphs and the class for which ▫$J_G$▫ satisfies (ii) is a proper superclass of distance hereditary graphs. We also give an axiomatic characterization of chordal and Ptolemaic graphs. |
Secondary keywords: |
matematika;teorija grafov;prepovedani podgrafi;inducirana pot;intervalna funkcija;aksiomi vmesnosti;tetivni grafi;razdaljno dedni grafi; |
URN: |
URN:SI:UM: |
Type (COBISS): |
Not categorized |
Pages: |
str. 951-958 |
Volume: |
Vol. 313 |
Issue: |
iss. 8 |
Chronology: |
2013 |
ID: |
1476751 |