  A pair of rooted tangents -- defining a quantum triangle -- with an
associated quantum wave of spin 1/2 is proposed as the primitive to represent
and compute symmetry. Measures of the spin characterize how "isosceles" or how
"degenerate" these triangles are -- which corresponds to their mirror or
parallel symmetry. We also introduce a complex-valued kernel to model
probability errors in the parameter space, which is more robust to noise and
clutter than the classical model.
