This dissertation determines the fusion rules for the fixed-point vertex operator algebra π π4 πΏ2 , where πΏ2 denotes the rank-one even lattice satisfying (πΌ, πΌ) = 2. The main idea is to identify certain irreducible π + β€π -modules as direct sums of irreducible π π4 πΏ2 -modules. These identifications allow us to compute the relevant entries of the π-matrix for π π4 πΏ2 . Applying the Verlinde formula, we then obtain the complete fusion rules for π π4 πΏ2 .
