Determination of the 2- cocycles for the three point Witt algebra

We provide formulas for computing the cocycles on a 3-point Witt algebra Der®, using an isomorphism between two 3-point algebras Der® and Der(S), where the cocycle is already defined. These cocycles can be used to construct universal central extensions and the 3-point Virasoro, which are useful for the representation theory of a 3-point current algebra. The computations determining the cocycles on Der® involve elegant applications of the Chu-Vandermonde convolution and other identities for sums of binomial coefficients.