Unequal piece widths change the shape and legal slice positions. An introduction to cube shape, layer arrangement, parity and the puzzle’s own notation.
In this guide
Wide corners, narrow edges
Square-1 has unequal sectors above and below a divided middle. A slice is possible only when no piece crosses its cut line. Corners occupy 60° and edges 30°.
Position as text
Geometrically calculated 3D teaching view. Square-1: three-dimensional cube shape with 60° corners, 30° edges and a divided middle layer.
Further reading: Jaap Scherphuis: Square-1
1 · Restore cube shape
Arrange sectors by width before colour. Find legal slice lines and regroup wide and narrow pieces until both layers are square again. A shape table helps identify the current outline. Do not try to force a wide piece through a blocked slice.
2 · Put colours on the correct layers
Separate the two broad face colours and align the middle layer, then permute corners and edges within the layers. Use restored cube shape after each full algorithm as a checkpoint; intermediate positions may temporarily change shape.
3 · Notation and parity
The notation (a,b) gives upper and lower turns in 30° units; / denotes the slice. Take signs and viewing directions from the same guide. An odd remaining permutation requires an appropriate Square-1 parity algorithm, not a 3×3 corner algorithm. Square-2 subdivides the wide corner sectors and changes the shape problem.