  We prove variation-norm estimates for the Walsh model of the truncated
bilinear Hilbert transform, extending related results of Lacey, Thiele, and
Demeter. The proof uses analysis on the Walsh phase plane and two new
ingredients: (i) a variational extension of a lemma of Bourgain by
Nazarov-Oberlin-Thiele, and (ii) a variation-norm Rademacher-Menshov theorem of
Lewko-Lewko.
