"a" [0, 1]
"b" [0, 1, 2]
"c" [0, 1, 2]
"d" [0, 1]

"a" 0 -> 1 when "d"=1
"a" 1 -> 0 when "b"=2


"b" 0 -> 1 when "c"=0 
"b" 0 -> 2 when "d"=1
"b" 1 -> 2 when "d"=1
"b" 2 -> 0 when "d"=0

"c" 0 -> 1 when "b"=2
"c" 0 -> 2 when "a"=0 and "b"=1
"c" 1 -> 0 when "a"=1

"d" 0 -> 1 when "a"=1 and "b"=0
"d" 1 -> 0 when "c"=2

initial_context "a"=0, "b"=1, "c"=0, "d"=1