I will discuss about the complexity of completing a partially filled Latin
Square(http://en.wikipedia.org/wiki/Latin_square ).
Our initial problem will be to complete a variation of incomplete Latin
Square where each row is either complete or empty. We will show that by
applying Hall's Marriage Theorem
(http://en.wikipedia.org/wiki/Hall%27s_marriage_theorem) and Bipartite
Matching algorithm we can solve this problem in Polynomial time. We will
focus on some graph theory ideas while discussing this problem.
And Finally we will prove that the complexity of filling any incomplete
Latin Square is NP-Complete. We will follow the proof from this paper
http://dx.doi.org/10.1016%2F0166-218X%2884%2990075-1
Thanks & Regards,
satej