How to remove unneeded constraints

*To*: mathgroup at smc.vnet.net*Subject*: [mg87904] How to remove unneeded constraints*From*: Kristian Schmidt <kristian at kreutz.us>*Date*: Sat, 19 Apr 2008 23:50:19 -0400 (EDT)

Hello The problem I am working on is a pretty large problem, which I am solving by dividing it into a lot of subproblems. As such, I have a large list of constraints that apply to the entire problem, but are not relevant for each individual subproblem. This becomes a problem when I use Refine, as it takes a very long time when you have a lot of conditions, even though the conditions don't pertain to the problem. Example: In[25]:= Table[Timing@Refine[p>q,Map[Subscript[x,#]>0&,Range[i]]],{i,1000,5000,1000}] Out[25]= {{0.547,p>q},{1.797,p>q},{3.875,p>q},{8.594,p>q},{10.468,p>q}} And it only gets worse. However, for each individual call to Refine I make, I only need a small subset of the total constraints. So what I want to do is something like this: expr = some expression of n different variables; cond = DeleteCases[totalConstraints, all cases which do not contain a variable from expr]; result = Refine[expr,cond]; I have no idea how to construct a pattern powerful enough to do what is required for the DeleteCases call, though. All of the variables are of the form Subscript[s,_,_,_] or Subscript[b,_,_] and the conditions can also contain expressions of several variables. I'd be most grateful for any help. Thank you.