Can the following picture be drawn without lifting the pen from the paper or retracting?

Question

Can the following picture be drawn without lifting the pen from the paper or retracting?

Answer 1

Definitely not, as A,B,C,E all have an odd number of incident paths.

--- rk

Answer 2

Imagine vertices as nodes of a graph and lines joining them as edges. Now, a graph can be drawn without lifting the pen from the paper or retracting if it has a Eulerian Path.

A graph has a Eulerian path if
1. Every node has even degree (even number of edges)
2. Exactly two nodes have odd degree and other's have even degree.

The degree is the count of edges passing through the vertex.

In your case, this fails, as this drawing has more than 2 vertices with odd degrees