  ZX-calculus is a high-level graphical formalism for qubit computation. In
this paper we give the ZX-rules that enable one to derive all equations between
2-qubit Clifford+T quantum circuits. Our rule set is only a small extension of
the rules of stabilizer ZX-calculus, and substantially less than those needed
for the recently achieved universal completeness. One of our rules is new, and
we expect it to also have other utilities.
  These ZX-rules are much simpler than the complete of set Clifford+T circuit
equations due to Selinger and Bian, which indicates that ZX-calculus provides a
more convenient arena for quantum circuit rewriting than restricting oneself to
circuit equations. The reason for this is that ZX-calculus is not constrained
by a fixed unitary gate set for performing intermediate computations.
