Network in Graph Theory

Vertex

A point in a network, joined to others by edges.

EnglishVertex
Bahasa MelayuBucu
中文顶点

How it is used

In a network of five towns A, B, C, D and E joined by roads, each town is a vertex, so the network has 5 vertices. If roads run A–B, A–C and A–D, then vertex A is joined to three other vertices.

Where it shows up in SPM

Appears in the Network in Graph Theory chapter (Form 5). In Paper 1 you count vertices or read them from a diagram; in Paper 2 you draw a network and identify vertices before working out degrees or finding a shortest route.

Don't confuse it with

EdgeA vertex is a point (a dot), while an edge is the line joining two vertices; do not count a connecting line as a vertex.
Node in a tree diagramA probability tree diagram branches to show outcomes, whereas a vertex in graph theory can have edges going in any direction, including forming loops.

Open the chapter: Network in Graph Theory →

Frequently asked questions

Is a vertex the same as a corner of a shape?

The word is the same, but in graph theory a vertex is any labelled point in a network, not just a geometric corner. It could represent a town, a person or a webpage, and it needs at least one edge to matter in a connected network.

What is the plural of vertex?

In English the plural is vertices, not vertexes. In Bahasa Melayu use bucu for both singular and plural, adding a number if needed, for example 5 bucu.

In Chinese it is 顶点 with a measure word such as 个.

How do I count vertices from a diagram quickly?

Count every distinct dot or labelled point, marking each once so you do not double-count. Where several lines cross, only count a crossing as a vertex if a dot is drawn there; a plain crossing of two edges is not a vertex.

Related terms

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