## What is meant by system of distinct representatives?

A subset of E formed by choosing a different ele- ment from each member of Q is called a system of distinct representatives of Q, or an SDR of Q. (Some· times, such as in [1], it is called a transversal of Q.

**What is sdr in graph theory?**

We usually abbreviate “system of distinct representatives” as sdr. We will analyze this problem in two ways, combinatorially and using graph theory.

### What is a matching in a graph?

A matching, also called an independent edge set, on a graph is a set of edges of. such that no two sets share a vertex in common. It is not possible for a matching on a graph with nodes to exceed edges. When a matching with. edges exists, it is called a perfect matching.

**What is edge coloring in graph theory?**

In graph theory, an edge coloring of a graph is an assignment of “colors” to the edges of the graph so that no two incident edges have the same color. For example, the figure to the right shows an edge coloring of a graph by the colors red, blue, and green.

## What is the difference between maximal and maximum matching?

The matching number of a graph G is the size of a maximum matching. Every maximum matching is maximal, but not every maximal matching is a maximum matching. The following figure shows examples of maximum matchings in the same three graphs.

**What is the difference between chromatic index and chromatic number?**

The smallest number of colors needed in a (proper) edge coloring of a graph G is the chromatic index, or edge chromatic number, χ′(G). The chromatic index is also sometimes written using the notation χ1(G); in this notation, the subscript one indicates that edges are one-dimensional objects.

### What is chromatic index?

The edge chromatic number, sometimes also called the chromatic index, of a graph is fewest number of colors necessary to color each edge of. such that no two edges incident on the same vertex have the same color. In other words, it is the number of distinct colors in a minimum edge coloring.

**What will be the chromatic number for a tree having more than 1 vertex?**

2 chromatic

Explanation: The minimum number of colors required for proper vertex coloring of graph is called chromatic number. So every tree having more than 1 vertex is 2 chromatic.

## How many unique Colour will be required for vertex Colouring of the following graph?

How many unique colors will be required for vertex coloring of the following graph? Explanation: The given graph will require 4 unique colors so that no two vertices connected by a common edge will have the same color.

**What is chromatic number and chromatic index?**

### What will be the chromatic index of the following graph?

What will be the chromatic index of the following graph? Explanation: The given graph will require 3 unique colors so that no two incident edges have the same color. So its chromatic index will be 3.