Unknown symbol in a fuzzy logic equation

[cnyd]

Hi people

I study on image processing and fuzzy logic. When I working on histogram normalization, I saw an equation which includes a symbol 'U' letter. On the bottom of the 'U' (m=1) and on the top of the 'U' (K) is written. And i want to learn what its (U) mean.

Thanks in advance.

Cuneyd HELVACI

[Hurkyl]

It's the union of a bunch of objects; it's exactly analogous to using \sum_{i=1}^k a_i to denote a bunch of additions.

[MathematicalPhysicist]

i believe this will help:
http://mathworld.wolfram.com/Union.html