From: Martin Mares Date: Sat, 30 Aug 2008 14:03:41 +0000 (+0200) Subject: Minor fixes to chapters 3 and 6. X-Git-Tag: v2~3 X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=ff49cabd35d3743ff060887a7fbf7ff15306691b;p=saga.git Minor fixes to chapters 3 and 6. --- diff --git a/TODO b/TODO index 27cb653..a76d1b8 100644 --- a/TODO +++ b/TODO @@ -18,28 +18,19 @@ Typography: Diaz: > 2: simplify, remove proof sketches -- 3: intro: replace "efficient" by "linear" -- 3.1.7, 3.1.10: skip proof -- 3.3: do we really need the full Komlos's result? -- 3.3.17: maxflow: shouldn't Karzanov be cited, too? -- 3.5.1: does the first alg give any insight? -- 3.5.1: mention geometric distribution -- 5.4.6: could we give a simple proof? -- 5: mention graphs with moving vertices? -- 6: mention d-regular graphs -- 6: two monographs on Euclidean MST - M. Steel: Probability theory and combinatorial optimization, SIAM 1997 - J. Yukich: Probability theory of classical Euclidean optimization problems, Springer 1998 +> 3.1.7, 3.1.10: skip proof +> 3.5.1: does the first alg give any insight? +> 5: mention graphs with moving vertices? Patrice: -- Remark on 2.5.1: polynomial time could be replaced by sub-exponential time. +> Remark on 2.5.1: polynomial time could be replaced by sub-exponential time. - For 1.5.6, you should probably quote D. Cheriton and R.E. Tarjan. Finding Minimum Spanning Trees. SIAM J. on Comp. 5(4) (1976) pp. 724-742. who gave a linear time algorithm for planar graphs, extended by Tarjan in 1983 to proper minor closed classes (both quoted by Gustedt). [XXX: Cannot get the paper.] -- In 3.1.12 and 3.1.16, you should make explicit the dependence of the +> In 3.1.12 and 3.1.16, you should make explicit the dependence of the running time with respect, for instance, to the Hadwiger number of the graph or to the maximal density nabla(G) of a minor of the graph, as considering a minor closed class or another does not change the diff --git a/adv.tex b/adv.tex index d56f58c..a5a1e13 100644 --- a/adv.tex +++ b/adv.tex @@ -8,7 +8,7 @@ The contractive algorithm given in Section~\ref{contalg} has been found to perform well on planar graphs, but in the general case its time complexity was not linear. -Can we find any broader class of graphs where this algorithm is still efficient? +Can we find any broader class of graphs where this algorithm is still linear? The right context turns out to be the minor-closed graph classes, which are closed under contractions and have bounded density. @@ -57,12 +57,11 @@ guarantees that we can always find a~finite set of forbidden minors: \thmn{Excluded minors, Robertson \& Seymour \cite{rs:wagner}} For every non-trivial minor-closed graph class~$\cal C$ there exists a~finite set~$\cal H$ of graphs such that ${\cal C}=\Forb({\cal H})$. +\qed -\proof This theorem has been proven in a~long series of papers on graph minors culminating with~\cite{rs:wagner}. See this paper and follow the references to the previous articles in the series. -\qed \para For analysis of the contractive algorithm, @@ -1128,8 +1127,8 @@ The number of $F$-nonheavy edges is therefore equal to the total number of the c flips in step~2 of this algorithm. We also know that the algorithm stops before it adds $n$~edges to~$F$. Therefore it flips at most as many coins as a~simple random process that repeatedly flips until it gets~$n$ heads. As waiting for -every occurrence of heads takes expected time~$1/p$, waiting for~$n$ heads -must take $n/p$. This is the bound we wanted to achieve. +every occurrence of heads takes expected time~$1/p$ (the distribution is geometric), +waiting for~$n$ heads must take $n/p$. This is the bound we wanted to achieve. \qed \para diff --git a/appl.tex b/appl.tex index 802198f..f9d59ab 100644 --- a/appl.tex +++ b/appl.tex @@ -103,6 +103,10 @@ based on the sweep-line technique and the Red rule. For other variations on the geometric MST, see Eppstein's survey paper \cite{eppstein:spanning}. +There are also plentiful interesting results on expected properties of the +Euclidean MST of various random point configurations. These are well covered +by the monographs of Steele \cite{steele:ptco} and Yukich \cite{yukich:pteucl}. + \paran{Steiner trees} The constraint that the segments in the previous example are allowed to touch each other only in the given points looks artificial and it is indeed uncommon in diff --git a/biblio.bib b/biblio.bib index acb1f8c..ad43a45 100644 --- a/biblio.bib +++ b/biblio.bib @@ -1569,3 +1569,22 @@ pages={282--285}, year={1951} } + +@book { steele:ptco, + author = "J. Michael Steele", + title = "{Probability Theory and Combinatorial Optimization}", + series = "{CMBS-NSF Regional Conference Series in Applied Mathematics}", + volume = 69, + year = "1987", + publisher = "Society for Industrial and Applied Mathematics" +} + +@book{ yukich:pteucl, + title={{Probability Theory of Classical Euclidean Optimization Problems}}, + author={Yukich, J.E.}, + year={1998}, + publisher={Springer}, + publisher = {Springer Verlag}, + volume={1675}, + series={{Lecture Notes in Math}}, +}