The point at the very middle of the

**graph**is**called**the origin, and its coordinates are (0, 0), because it's 0 units away from the**center**of the**graph**in both directions. If we draw a line on the**graph**, sometimes the line crosses either the x-axis or the y-axis.Similarly, what is in the center of a tree?

In discrete mathematics, a centered

**tree**is a**tree**with only one**center**, and a bicentered**tree**is a**tree**with two centers. Given a graph, the eccentricity of a vertex v is defined as the greatest distance from v to any other vertex. A**center**of a graph is a vertex with minimal eccentricity.What is the spread of a graph?

The center is the median and/or mean of the data. The

**spread**is the range of the data. And, the shape describes the type of**graph**. The four ways to describe shape are whether it is symmetric, how many peaks it has, if it is skewed to the left or right, and whether it is uniform.What is the eccentricity of a graph?

The

**eccentricity of a graph**vertex in a connected**graph**is the maximum**graph**distance between and any other vertex of . For a disconnected**graph**, all vertices are defined to have infinite**eccentricity**(West 2000, p. 71). The maximum**eccentricity**is the**graph**diameter. Harary, F.**Graph**Theory.