Bidirectional Cycle (XY-Cycle)
The cells {0} form a bidirectional cycle: there are exactly
two ways of placing the values in these cells, forming two
different possible configurations. Some values appear in a
row, column or box regardless of which configuration is correct. Because
one of the two configurations must be correct, other occurrences of
these values can be removed from these rows, columns or boxs.
The two configurations of the bidirectional cycle are enforced by two
complementary, circular chains of implications. The details of each chain
are given below.
Cycle details, forward direction (View 1):
{3}
Cycle details, reverse direction (View 2):
{4}