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Halfmax image
Pattern type Spacefiller
Number of cells 904
Bounding box 65×80
Discovered by Jason Summers
Year of discovery 2005

Halfmax (or half-spacefiller[1]) is a pattern that acts as a spacefiller in half of the Life plane. It was found by Jason Summers in May 2005. It expands in three directions at c/2, producing a triangular region that grows to fill half the plane. All previously-known spacefillers had been diamond-shaped, expanding at c/2 in all four cardinal directions to fill the entire plane.[2]

The version shown to the right was found by Summers on May 21, 2005. Two less compact versions, shown below, were also found earlier that same month.

Image gallery

Halfmax at generation 70
The earliest version of halfmax, found by Jason Summers
RLE: here
The next version of halfmax, found by Hartmut Holzwart
RLE: here


Halfmax expanding over about 200 generations

See also


  1. Jason Summers' jslife pattern collection.
  2. Dave Greene (May 9, 2005). "Extensible Wickstretchers and HALFMAX". Game of Life News. Retrieved on May 26, 2009.