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Cycles in family tree software 1425 389 1 am the developer of some family tree software (written in C and Qt). I had no problems until one of my customers mailed me a bug report. The problem is that he has two children with his own daughter, and, as a result, he can’t use my software because of errors. Those errors are the result of my various assertions and invariants about the family graph being processed (for example, after walking a cycle, the program states that X can’t be both father and grandfather of Y). How can I resolve those errors without removing all data assertions? c graph cycle assertions family-tree