Course: Advanced Topics in Graph Algorithms Fall 1991/2 ------------------------------------------------------- Oct 16 1 basic graph concepts intersection graphs interval graphs sneak preview (Gloumbic Ch. 1) Oct 23 2 basic algorithmic concepts and ata structures BFS, DFS Transitive tournaments and topological sorting (Golumbic Ch. 2) Oct 30 3 The Perfect Graph Theorem (Golumbic Ch 3.2) Nov 6 4 Trigangulated Graphs: *Fulkerson-Gross, Dirac Thms. *perfect elim. order algorithm: Lex BFS validity (Golumbic Ch. 4.1-3) Nov 13 5 Trigangulated Graphs: *Lex BFS complexity *Alg to verify a given elim order is perfect *Triangulated graphs as intersection graphs (Walter-Gavril theorem except 1=>3) (Golumbic Ch. 4.3-5) Nov 20 6 Trigangulated Graphs: *Triangulated graphs as intersection graphs (Walter-Gavril theorem 1=>3) (Golumbic Ch. 4.5) *Minimum Fill In is NP-complete (Yannakakis) *Triangulated graphs are perfect (Golumbic Ch. 4.6) Nov 27 7 Trigangulated Graphs: *Algs for comuting chromatic and stability numbers on triangulated graphs (Golumbic Ch. 4.7) Comparability Graphs: * implication classes and Gamma-chains (Golumbic Ch. 5.1) Dec 04 8 Comparability Graphs: * Uniquely Partially Orderable graphs (Golumbic Ch. 5.2) * G-decomposition and characterizations (first part of Golumbic Ch. 5.4) Dec 11 9 Guest lecture: Marty Dec 18 10 Comparability Graphs: * Characterization Theorem * Recognition algorithm and complexity * perfectness and Dilworth theorem. * Algorithm for max weighted clique * partial order dimension (Golumbic Ch. 5.4-7) Dec 25 11 Interval Graphs: * Gilmore-Hoffman Characterization Thm (Golumbic Ch. 8.2) * Lekkerkerekr-Boland Characterization Thm (Fishburn CH. 3.4) Jan 1 12 Temporal Reasoning: * Allen's model, ISAT, MLP, ACSP. * Interval sandwich is NP-complete. * polynomial algorithm for A3-<>. (Golumibc-Shamir 90) Jan 8 13 Interval Graphs: * consecutive and circular ones recognition, PQ trees (no proofs) * Preference and Indifference: semiorder, Roberts' theorem (Golumbic Ch. 8.3,5) * split graphs (survey) (Golumbic Ch. 6) Jan 16 14 brief reviews: * Circular arc Graphs (Golumbic Ch. 8.6) * permutation graphs (Golumbic Ch. 7) * perfect elimination bipartite graphs * chordal bipartite graphs. (Golumbic Ch. 11) * Greedily solvable network flow problems (Adler-Hoffman-Shamir 90)