# Unknown symbol in a fuzzy logic equation

1. Jul 17, 2004

### 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.

Cuneyd HELVACI

2. Jul 17, 2004

### Hurkyl

Staff Emeritus
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.

3. Jul 17, 2004