> I'm a greenhorn in programming and modelling and I hope somebody could
> help me!

> I have the following problem with xPress Mosel IVE:

> I have a linear program with the following side condition: (Transport
> condition)

> y1l >= LB1 or y1l = 0

> l ... stands for distribution center or consumer
> j ... stands for factory 1 or 2
> t ... stands for Week 1 to 4

> y1l ... Products which are transported from factory 1 to the
> distribution center or to the consumer

> LB1...The required amount on products which should be transported from
> factory 1 to the distribution center or to the consumer

> I have input the side condition (Transport condition) in xPress Mosel
> IVE as the following but there is always the error message that
> something is wrong with the operator or:

> forall(l in indexl, j in indexj, t in indext) do
> y1l(l, j, t) >= LB1(l, j) or y1l(l, j, t) = 0
> end-do

> I think that I must input the or condition in another way but I didn't
> know how!?

> I'm very happy and thankful if somebody could help me,
> best regards,

> Mags