Computing the unknotting numbers of certain pretzel knots.

We compute the unknotting number of two infinite families of pretzel knots, P ( 3 , 1 , … , 1 , b ) (with b odd and at least 3 and an odd number of 1s) and P ( 3 , 3 , 3 c ) (with c positive and odd). To do this, we extend a technique of Owens using Donaldson's diagonalization theorem, and one of Traczyk using the Jones polynomial, building on work of Lickorish and Millett. [ABSTRACT FROM AUTHOR]