\[st(j+1,p,m,w,c,h) \ge x(j+1,p,m,w,c,h) \cdot ft(j,p,d,ww,z,h)\] \[ \begin{eqnarray} ft &\in &\;\;\mathbb{Z}_0 &\text{[= finish time]}\\ st &\in &\;\;\mathbb{Z}_0 &\text{[= start time], and}\\ x &\in &\{0,1\} &\text{[= decision variable if operation j+1}\\ & & &\quad\;\text{of part p on machine m with worker w}\\ & & &\quad\;\text{in cell c and horizon h is done or not]}\\ \end{eqnarray}\\ \] \[\ldots\text{all are decision variables.}\] 
st(j+1,p,m,w,c,h)≥⋅ft(j,p,d,ww,z,h)  M(1x(j+1,p,m,w,c,h)) does this solve the problem? usually this arises in Job Shop Scheduling models if I am not mistaken. But that causes numerical instabilities, answered 04 Jul '12, 05:51 ShahinG i think it will work,thanks a lot
(04 Jul '12, 06:01)
girl
1
For performance (and stability) reasons, try to pick M as small as is safely possible in each constraint (something like worstcase makespan).
(04 Jul '12, 17:21)
Paul Rubin ♦♦
yea im working on somehow scheduling model,thanks for ur help
(05 Jul '12, 16:08)
girl

very efficient, @girl, but too efficient for me. could you give a little more context, tell us what kind your variables are (continuous, integer, binary?), where does the constraint come from, etc.? Thanks.
oh yes,x is binary and st and ft are integer.ft=finish time.st=start time.x is decision variable if operation j+1 of part p on machine m with worker w in cell c and horizon h is done or not
@fbahr thanks for editting...