In extra depth search, solver should reject a branch if it encounters a cycle, because a position isn't legal if the search gets stuck in a cycle of retractions.
More precisely, in order that no possible last moves are omitted, the entire cycle (after the first node) should lie within the extra depth portion of the search. More aggressive pruning of cycles (pruning within the solve depth) is also implemented as an option, but it can cause some solutions to be omitted, if there is a cycle within the solution itself.
In extra depth search, solver should reject a branch if it encounters a cycle, because a position isn't legal if the search gets stuck in a cycle of retractions.
More precisely, in order that no possible last moves are omitted, the entire cycle (after the first node) should lie within the extra depth portion of the search. More aggressive pruning of cycles (pruning within the solve depth) is also implemented as an option, but it can cause some solutions to be omitted, if there is a cycle within the solution itself.