always figure that with a good algorithm you can just wait 18 or 36 months and the computers will be fast enough so you can use your algorithm then.

Gintaris Reklaitis: From the perspective of combinatorial problems arising in supply-chain management and scheduling, doubling of computer time every 18 months will not suffice. These are problems for which computational effort grows exponentially with problem size, at least in the worst case. For the kinds of increasingly larger applications that people want to solve in these domains, waiting for the hardware to become faster is not the solution. The improvements must be found through algorithm research.

David Smith: I do not know. I used to have a group that did supply chain optimization, and in the reorganization that group went elsewhere. I would say that for a lot of very good sized, really significant supply chain problems that we were tackling, we were getting solutions in a couple of hours. The problem that we ran into was that, for reasons I could not understand, the people who wanted the answers were upset because they had to wait 2 hours for them; they did not realize that the business time scale that were dealing with probably involved days or weeks. These guys are used to running Excel spreadsheets in minutes, and the fact that they had posed a problem to the computer and had to wait for 2 hours for an answer was a very difficult cultural thing for them to deal with.

In general, business people are not trained in optimization, and they are usually very defensive when we bring those kinds of solutions to them. So it is really an educational problem that we have internally.

Judith Hempel: Are they senior staff of long standing?

David Smith: No. Neither were the people who were solving those problems for me. The young people in support positions in DuPont supplying that kind of information to business managers do not have the right kind of training and background to solve those problems. Solving the problem for them turns out to be an iterative process because they do not really understand how much information they have to give us so we can give them a good solution to their business problem.



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