# This program test whether the tape contains a correct equation in the form
# |||| + ||| = |||||||
# the program stops at the side where more | are or at the = sign if the
# equation is correct.
0 | | r 1	replace + with I and test syntax for ||* + ||* = |*
0 + + r 99
0 = = r 99
0 _ _ r 99
1 | | r 1
1 + | r 2
1 = = r 99
1 _ _ r 99
2 | | r 3
2 + + r 99
2 = = r 99
2 _ _ r 99
3 | | r 3
3 + + r 99
3 = = r 4
3 _ _ r 99
4 | | r 4
4 + + r 99
4 = = r 99
4 _ _ l 5	end syntax test for ||* + ||* = |*
5 | | l 5	go left to beginning of tape
5 + + r 99
5 = = l 5
5 _ _ r 6
6 | _ r 7	delete leftmost |
6 + + r 99
6 = = r 99
6 _ _ r 99
7 | | r 7	go right, to end of tape
7 + + r 99
7 = = r 7
7 _ _ l 8
8 | _ l 5	delete rightmost |
8 + + r 99
8 = = l 9
8 _ _ r 99
9 | | l 99
9 + + l 99
9 = = l 99
9 _ _ r 10	accept only if there are no blanks left to the left of =