Prove that every tree has at most one perfect matching.

[hero]

Prove that every tree has at most one perfect matching.

I am sure that I have to use some sort of induction or contradiction but i'm not sure.

 

[ikoukas]

Prove that every tree has at most one perfect matching.

What do you mean by a "perfect matching"?

It might help if you could give an example, in addition to the definition. Thank you!