|View static image|
|Pattern type||Strict still life|
|Number of cells||9|
|Year of discovery||1971|
Integral sign (or simply integral) is a 9-bit still life found in 1971. It can eat gliders the same way that an Eater 1 eats, from either end. If the middle cell of the vertical line is removed, it becomes a bipole.
Integral sign is the eighteenth most common still life on Adam P. Goucher's Catagolue, being less common than long ship but more common than shillelagh. Among all still lifes with 9 cells, it is the absolute most common, followed by trans-boat with tail. It is also the twenty-fifth most common object overall on Catagolue.
The most common way for an integral to form is for a pi-heptomino to hit an object at a specific location. A block is shown below; in general, any object that has exactly two cells in its leftmost column works, although in some cases, the integral is destroyed after being created.
|A pi-heptomino hitting a block, creating an integral in its ash|
(click above to open LifeViewer)
RLE: here Plaintext: here
Despite having rotational symmetry, the integral is no more common in rotationally symmetric soups than asymmetric ones. This is because the integral typically forms as described above. In soups with empty space, integrals typically form at the edge of a soup; this makes integrals less common in toruses and larger soups.
Integrals replace fishhooks in natural oscillators at a ratio of about 5 fishhooks for 1 integral.
All strict still lifes with a population of 20 or fewer cells, as well as all oscillators and spaceships with 16 or fewer cells, are known to be glider-constructible. A glider synthesis of this object can be found in the infobox to the right.