I'm pretty sure it means that you can't cross the wires (0, 1) and (1, 2) at once, just (0, 1) and (2, 3): 

# allowed:
0 _  _ 1
   \/
1 _/\_ 0

2 _  _ 3
   \/
3 _/\_ 2


# disallowed, ambiguous:
0 _  _ 1
   \/
1 _/\_ 0
   \/
2 _/\ _ 3

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Perl 6 - the future is here, just unevenly distributed

In reply to Re^2: The Perl 6 Coding Contest 2012 by moritz
in thread The Perl 6 Coding Contest 2012 by moritz

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