Covariance vs. contravariance with respect to class inheritance

Question

What is the meaning of the concepts \'covariance\' and \'contravariance\'?

Given 2 classes, Animal and Elephant (which inherits from

Answer 1

Have a look at this overview of covariance and contravariance in C# 4.0 and see if that helps:

http://blogs.msdn.com/charlie/archive/2008/10/27/linq-farm-covariance-and-contravariance-in-visual-studio-2010.aspx