diff --git a/chapter15.tex b/chapter15.tex index 37bb3c1..27f44df 100644 --- a/chapter15.tex +++ b/chapter15.tex @@ -29,7 +29,7 @@ For example, consider the following graph: \path[draw,thick,-] (3) -- node[font=\small,label=left:3] {} (6); \end{tikzpicture} \end{center} -A possible spanning tree for the graph is as follows: +One spanning tree for the graph is as follows: \begin{center} \begin{tikzpicture}[scale=0.9] \node[draw, circle] (1) at (1.5,2) {$1$}; @@ -67,12 +67,9 @@ is 20, and such a tree can be constructed as follows: \node[draw, circle] (6) at (5,1) {$6$}; \path[draw,thick,-] (1) -- node[font=\small,label=above:3] {} (2); -%\path[draw,thick,-] (2) -- node[font=\small,label=above:5] {} (3); -%\path[draw,thick,-] (3) -- node[font=\small,label=above:9] {} (4); \path[draw,thick,-] (1) -- node[font=\small,label=below:5] {} (5); \path[draw,thick,-] (5) -- node[font=\small,label=below:2] {} (6); \path[draw,thick,-] (6) -- node[font=\small,label=below:7] {} (4); -%\path[draw,thick,-] (2) -- node[font=\small,label=left:6] {} (5); \path[draw,thick,-] (3) -- node[font=\small,label=left:3] {} (6); \end{tikzpicture} \end{center} @@ -92,14 +89,11 @@ example graph is 32: \node[draw, circle] (4) at (6.5,2) {$4$}; \node[draw, circle] (5) at (3,1) {$5$}; \node[draw, circle] (6) at (5,1) {$6$}; -%\path[draw,thick,-] (1) -- node[font=\small,label=above:3] {} (2); \path[draw,thick,-] (2) -- node[font=\small,label=above:5] {} (3); \path[draw,thick,-] (3) -- node[font=\small,label=above:9] {} (4); \path[draw,thick,-] (1) -- node[font=\small,label=below:5] {} (5); -%\path[draw,thick,-] (5) -- node[font=\small,label=below:2] {} (6); \path[draw,thick,-] (6) -- node[font=\small,label=below:7] {} (4); \path[draw,thick,-] (2) -- node[font=\small,label=left:6] {} (5); -%\path[draw,thick,-] (3) -- node[font=\small,label=left:3] {} (6); \end{tikzpicture} \end{center} @@ -107,15 +101,14 @@ Note that a graph may have several minimum and maximum spanning trees, so the trees are not unique. -This chapter discusses algorithms -for constructing spanning trees. -It turns out that it is easy to find -minimum and maximum spanning trees, -because many greedy methods produce optimals solutions. -We will learn two algorithms that both process +It turns out that several greedy methods +can be used to construct minimum and maximum +spanning trees. +In this chapter, we discuss two algorithms +that process the edges of the graph ordered by their weights. -We will focus on finding minimum spanning trees, -but similar algorithms can be used for finding +We focus on finding minimum spanning trees, +but the same algorithms can find maximum spanning trees by processing the edges in reverse order. \section{Kruskal's algorithm}