one strategy involves grouping similar edge pieces into solid strips, and centers into one-colored blocks. this allows the cube to be quickly solved with the same methods one would use for a 3×3×3 cube. because the permutations of the corners, central edges and fixed centers have the same parity restrictions as the 3×3×3 cube, once reduction is complete the parity errors seen on the 4×4×4 and 6×6×6 cannot occur on the 7×7×7.