why can´t it be an undirected graph?

Question

I´m stuck here with a question I cannot resolve. the question is why can´t this matrix be an undirected graph? [ [0,1,0], [1,1,1], [0,0,0] ] I was told by my teacher that it can´t be an undirected graph. I have to explain why but I really don´t know.

Answer 1

The second node is connected to the third node. The third node is not connected to the second node. This is a one-way connection, which can only happen in directed graphs.

Basically, an undirected graph matrix is always a symmetric matrix - and your matrix is not symmetric.