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# What is the minimum number of edges and vertices possible in a non planar graph?

## What is the minimum number of edges and vertices possible in a non planar graph?

A plane graph having ‘n’ vertices, cannot have more than ‘2*n-4’ number of edges. Hence using the logic we can derive that for 6 vertices, 8 edges is required to make it a plane graph. So adding one edge to the graph will make it a non planar graph. So, 6 vertices and 9 edges is the correct answer.

### What is the smallest non planar graph?

It turns out that K_{3,3} and K_5 are the “smallest” non-planar graphs in that every non-planar graph contains them.

#### What is the minimum number of edges possible in a simple planar graph with 4 vertices?

If the graph must be connected, the minimum number of edges would be 4. If the graph need not be simple, then there is no maximum number of edges. If the graph must be simple, then the maximum number of edges would be 9, since K5 is not planar, but K5−e is.

Why is K5 not planar?

K5: K5 has 5 vertices and 10 edges, and thus by Lemma 2 it is not planar. K3,3: K3,3 has 6 vertices and 9 edges, and so we cannot apply Lemma 2.

What is a non planar graph?

Non-planar graph − A graph is non-planar if it cannot be drawn in a plane without graph edges crossing.

## How do you show a graph is not planar?

To show that a graph is planar, one has to produce a planar embedding of the graph. However, to show that a graph is non planar one has to show that either the graph satisfies a property that is not satisfied by any planar graph , or out of all possible diagrams of G, no one is a planar embedding.

### How do you know if a graph is non planar?

Non-Planar Graph: A graph is said to be non planar if it cannot be drawn in a plane so that no edge cross. Example: The graphs shown in fig are non planar graphs. These graphs cannot be drawn in a plane so that no edges cross hence they are non-planar graphs.

#### What is the minimum number of edges necessary in a simple planar graph with 15 regions?

In a simple planar graph, degree of each region is >= 3. So, we have 3 x |R| <= 2 x |E|. Thus, Minimum number of edges required in G = 23. Get more notes and other study material of Graph Theory.

What is a non-planar graph?

Is K3 planar?

The graph K3,3 is non-planar.

## Which is non planar?

: not planar : not lying or able to be confined within a single plane : having a three-dimensional quality … there is no way of redrawing this circuit so that none of the elements cross. This, therefore, is an example of a nonplanar circuit.—

### What is a non planar molecule?

Non-planar compounds are the compounds in which the atoms do not lie in the same plane.

#### What is a non planar graph with minimum number of vertices?

Non planar graph with minimum number of vertices have 9 edges, 5 vertices. A planar graph is a graph that can be embedded in the plane, that is it can be drawn on the plane in such a way that its edges intersect only at their endpoints.

Which is the unique non-1-planar graph with 18 edges?

The graph Q is a subgraph of G 3, G 4, and G 5, hence the graphs K 7 – G i, i = 3, 4, 5, are 1-planar. We obtain that K 7 – K 3 is the unique non-1-planar graph with 18 edges.

How to prove a graph is non-planar?

These graphs cannot be drawn in a plane so that no edges cross hence they are non-planar graphs. A graph is non-planar if and only if it contains a subgraph homeomorphic to K 5 or K 3,3 Example1: Show that K 5 is non-planar. Solution: The complete graph K 5 contains 5 vertices and 10 edges. Now, for a connected planar graph 3v-e≥6.

## How do you know if a graph is connected planar?

If a connected planar graph G has e edges and r regions, then r ≤ e. If a connected planar graph G has e edges, v vertices, and r regions, then v-e+r=2. If a connected planar graph G has e edges and v vertices, then 3v-e≥6. A complete graph K n is a planar if and only if n<5.