P1 = ["ABCD","CABD","ACDB","DACB","BCDA","ACBD",
         "ADCB","CDAB","DABC","BCAD","CADB","CDBA",
         "CBAD","ABDC","ADBC","BDCA","DCBA","BACD",
         "BADC","BDAC","CBDA","DBCA","DCAB"],
   Perms = permutations("ABCD"),
   % ...