2228.sagews

def rcd(g, ancilla): 
        
        # Maybe some Check Up here if g is of correct format        

        # Creating Graph
     G = Graph(g, boundary = ancilla)

        # Required Matrix and Vector Space, p-list and Field
     F = GF(2)
     p = G.vertices()    
     MS = MatrixSpace(F, G.order())
     V = VectorSpace(F, G.order())

     for x in G.get_boundary(): p.remove(x)   
     
        # Creating subspace
     SemiSubSpace = V.basis_matrix().matrix_from_rows(p).row_space()
     SubSpace = SemiSubSpace.direct_sum(SemiSubSpace)     

        # Creating Generator Matrix and Stabilizer Space
     adj = MS(G.adjacency_matrix())
     Mgenerator = block_matrix([MS.identity_matrix(), adj], ncols = 2)
     Stabilizer = Mgenerator.row_space()        

        # Projection onto spanned subspace
     TraceOut = Stabilizer.intersection(SubSpace)


     return TraceOut

@interact
def _(graph = input_box(default = {0:[1], 1:[2], 2:[3], 3:[4], 5:[0]}, label = 'Insert Graph here:',type = dict), ancilla = input_box(default = [0], label = 'Ancilla Vertices', type = list)):
     p = rcd(graph, ancilla)    
     Graph(graph).plot
     print p

Insert Graph here:  Ancilla Vertices