HeavisideLink
From OpenCog
The HeavisideLink is a kind of FunctionLink that represents the Heaviside step function. It is a functional version of the GreaterThanLink.
For example,
(HeavisideLink (MinusLink (NumberNode 2 3 4 5 6) (NumberNode 6 5 4 3 2)))
evaluates to
(NumberNode 0 0 0 1 1)
This is a vector representation of a greater-than operation on the two lists of numbers: the first three are not greater than, but the last two are greter than the corresponding numbers in the second row.