Knot doubling operators and bordered heegaard floer homology

We use bordered Heegaard Floer homology to compute the τ invariant of a family of satellite knots obtained via twisted infection along two components of the Borromean rings, a generalization of Whitehead doubling. We show that τ of the resulting knot depends only on the two twisting parameters and the values of τ for the two companion knots. We also include some notes on bordered Heegaard Floer homology that may serve as a useful introduction to the subject.