Tuesday, 27 May 2008

Coming into OR

I realise that I came into OR at an interesting time. I had studied mathematics as an undergraduate, and wondered what to do with the degree. (Both my parents had mathematics degrees; father was a scientific civil servant working with radar, mother had been a teacher; but neither career appealed to me.) A helpful careers advisor took me through some of the options, based on what I had told him of myself, and I duly applied -- and was accepted -- onto a one year postgraduate course in OR. At the time (early 1970's) there were still many of the pioneers of OR in UK industry and universities still around, and there was a good buzz of meetings and new ideas. The one-year course exposed me to the theory, but far more important, the philosophy of OR. I stayed on to do research, and then joined the staff at the University of Exeter where I have been ever since.
It was a pioneering time in Exeter, setting up an undergraduate programme in "Mathematical Statistics and OR" (MSOR for short) and we had some stimulating years with annual cohorts of 20 to 30 students, who wanted to "do something with their mathematical skills, but not a mathematics degree".
We developed links with industry and ran some fascinating projects; maybe more of these later, when I have time.
My postgraduate work centred on the water supply industry, and we encountered a problem which (like the supermarket cashiers problem) is simple to state, but leads to more complexity as one gets into it. A water supply reservoir has many purposes. First, to store water to supply the users. For that it ought to be full. Second, to restrain floods. For that it needs to have space in it, and not be full. Third, to provide recreation. For that, the level should not fluctuate much, under normal circumstances. So what should the reservoir manager's policy be about releasing water, both in the short term (when floods are imminent) and in the long term, when the weather is calm. How can forecasts help? The problem was nicknamed the "Noah and Joseph" problem, by reference to Noah who encountered floods (a short-term phenomenon) and Joseph who dealt with droughts (long-term).

Introducing myself and OR

This is the first item in the Blog of the IAOR editor. So it is a place to do some introductions. I am David Smith and one of my responsibilities is to edit IAOR, the International Abstracts in Operations Research. As I shall often refer to OR, I'd better explain. OR is the abbreviation for Operations Research or Operational Research, depending on where in the world you live. There are many places which define OR, so I will not waste space describing the subject in detail, but simply give one illustration.
From time to time, people ask me what I do.
First answer: "I work at the university".
Some people change the subject; others ask: "What subject?"
Second answer: "I teach a branch of mathematics."
More people change the subject, or admit that they did not get on with mathematics; however, some ask a little more.
So I explain that OR is not really a branch of mathematics, but a subject in its own right, which uses mathematics and other ideas to answer questions for business and commerce, either "What's best?" or "What happens if ...?" And my standard, simple illustration is the local supermarket, and the number of cashiers on duty. The best number is somewhere between too small and too many; too few, and the queues get big, and the customers start to go to another store; too many, and there are no queues, but the cashiers are not working fully. So there must be a "Right number" -- the problem is mathematical. But the number depends on the time of day, day of the week, month of the year. So you need to forecast the number of customers who will shop on different days at different times. More mathematics. And you need to devise a shift system for the staff of the store so that the full-time and part-time employees have regular work patterns. More mathematics (or OR!) So what started as a simple question, "How many?", has become a much larger problem for the company.
Having explained that, my audience starts to realise that OR is useful in their world, and I can recount other applications that often surprise and fascinate them.

I meant to introduce myself, but it has turned into an introduction to explaining OR to my dinner guests.