nonomino
Sign in to savethumb|right|A nonomino or Jigsaw puzzle|Jigsaw [[Sudoku puzzle, as seen in The Sunday Telegraph]] A nonomino (or enneomino or 9-omino) is a polyomino of order 9; that is, a polygon in the plane made of 9 equal-sized squares connected edge to edge. The name of this type of figure is formed with the prefix non(a)-. When rotations and reflections are not considered to be distinct shapes, there are 1,285 different free nonominoes. When reflections are considered distinct, there are 2,500 one-sided nonominoes. When rotations are also considered distinct, there are 9,910 fixed nonominoes.
Article
3 sectionsContents
- Symmetry
- Packing and tiling
- References
thumb|right|A nonomino or Jigsaw puzzle|Jigsaw [[Sudoku puzzle, as seen in The Sunday Telegraph]] A nonomino (or enneomino or 9-omino) is a polyomino of order 9; that is, a polygon in the plane made of 9 equal-sized squares connected edge to edge. The name of this type of figure is formed with the prefix non(a)-. When rotations and reflections are not considered to be distinct shapes, there are 1,285 different free nonominoes. When reflections are considered distinct, there are 2,500 one-sided nonominoes. When rotations are also considered distinct, there are 9,910 fixed nonominoes.
==Symmetry== The 1,285 free nonominoes can be classified according to their symmetry groups: 1,196 nonominoes have no symmetry. Their symmetry group consists only of the identity mapping. 38 nonominoes have an axis of reflection symmetry aligned with the gridlines. Their symmetry group has two elements, the identity and the reflection in a line parallel to the sides of the squares.