DETERMINISTIC MATH MODELS (550.251) HOMEWORK 5 FREQUENTLY ASKED QUESTIONS

GENERAL COMMENTS: Please remember to include HW4 problem 1 with this 
assignment.

1.  PROBLEM 2: I'm a little confused by what you mean by "wasted rolls" in
part (a).  Do you mean that we are trying to find the optimal pattern
and thus find the minimized wasted roll?

ANSWER: There are two types of waste in a cutting stock problem:

) Trim Loss: occurs when we create a pattern and we don't use all of the
available width. (e.g. the width is 100 units and the pattern is to cut 30
rolls of width 30.  Here the trim loss is 10 units)

2) Wasted Rolls: occurs when we exceed demand.  We should meet or exceed
demand, however, exceeding demand is not really useful because the
underlying assumption is that there is no one to sell the extra to.  Here
the waste is # extra rolls * width of extra rolls

So in part (a) you need to use a surplus variable for each constraint to
count the number of excess rolls created.  Then use this variable to
create an objective function that minimizes the loss due to wasted rolls.