Add remove_VOP method

clifford.py

@@ -12,6 +12,7 @@ from functools import reduce
 from util import cache_to_disk
 
 
+# TODO: make this more efficient / shorter
 def find_up_to_phase(u):
     """ Find the index of a given u within a list of unitaries, up to a global phase  """
     for i, t in enumerate(unitaries):
@@ -44,9 +45,13 @@ decompositions = ("xxxx", "xx", "zzxx", "zz", "zxx", "z", "zzz", "xxz",
 elements = {"x": qi.sqx, "z": qi.msqz}
 unitaries = [compose_u(d) for d in decompositions]
 conjugation_table, times_table = construct_tables()
+
+# TODO: generate these global names automatically via search
 sqx = 15
 msqz = 5
 
+
+
 if __name__ == '__main__':
     print find_up_to_phase(qi.sqx)
     print find_up_to_phase(qi.msqz)

cz.py

@@ -14,6 +14,17 @@ def local_complementation(g, vops, v):
     for i in g[v]:
         vops[i] = clifford.times_table[vops[i]][clifford.msqz]
 
+
+def remove_vop(g, vops, a, b):
+    """ Reduces VOP[a] to the identity, avoiding (if possible) the use of vertex b as a swapping partner """
+    free_neighbours = g[a] - {b}
+    c = b if len(free_neighbours) == 0 else free_neighbours.pop()
+    d = clifford.decompositions[a]
+    for v in reversed(d):
+        target = a if v == clifford.sqx else b
+        local_complementation(g, vops, target)
+
+
 if __name__ == '__main__':
     g, vops = graph()
     add_edge(g, 0, 1)