Add 4-boudnary experiment

experiments/cdc_4-boudaries.py

+#!/usr/bin/python
+
+"""
+Calculate a lower bound on the number of 4-boundaries
+of a linear representation of the number of circuit double
+covers.
+
+It uses cyclic ladder gadgets with sizes 2 up to 7 with
+permutations of all half-edges except the first one.
+This gives matrix of size 36 with rank 21.
+"""
+
+import sys, os
+sys.path.append(os.path.dirname(__file__) + "/..")
+
+from itertools import permutations
+from graph_tools.all import *
+
+
+LadderGadget = lambda k: CyclicLadder().gadget(k)
+ladders = list(map(LadderGadget, range(2, 8)))
+gadgets = [ l.permute((1,) + p) 
+  for l in ladders for p in permutations([2, 3, 4]) ]
+M = parameter_matrix(CircuitDoubleCover, gadgets)
+
+if __name__ == "__main__":
+  print("Matrix of size %i with rank %i" % (M.nrows(), M.rank()))
+