EUROPEAN
JOURNAL
OFOPERATIONAL
RESEARCH
ELSEVIER
European Journal of Operational Research 99 (1997) 207-219
What is my objective function?
1
Dominique de Werra
Ddpartement de Math~matiques, Ecole Polytechnique F~dgrale de Lausanne, CH-IO]5 Lausanne, Switzerland
Abstract
This paper expresses some of the views of the author about OR and his warm thanks to many friends. © 1997 Elsevier
Science B.V.
Keywords: Fun; Team-work; Enjoyment; Life sciences; Ants; Ducks; Strange objects
Mr. President, ladies and gentlemen, dear friends,
Besides the fact that one has the strange impression of attending one's own funeral, it is, as you may
imagine, not a v e r y comfortable situation to suddenly
become a member of the EURO medallists club.
In such circumstances a recipient may start his
speech by thanking the jury for the clever choice
they made and asking very discreetly why he had to
wait so many years before getting the award which
was his aim since his childhood (it is b y and large
for him a goal medal while the initials OR mean of
course the Obtained Reward).
Some nominees feel then that they have reached
the level of a Nobel Prize; having a Gold Medal, or
shortly GM, they are sure that they automatically
become a Grand Manitou (Fig. 1).
Having climbed (Fig. 2) to the Olympus of Science (they even talk of a God Medal), t h e y are
entitled to give to the world scientific community an
i Gold Medal Laureate Address, EURO XIV, Jerusalem, July
4, 1995.
0377-2217/97/$17.00 © 1997 Elsevier Science B.V. All rights reserVed.
PH S 0 3 7 7 - 2 2 1 7 ( 9 6 ) 0 0 3 93-1
Fig. 1. A grand Manitou.
208
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
extensive survey of their views of the universe - a
kind of tutorial on " M y own personal views on the
galaxy and its long term future" by John E. Pinkelgosh Jr., II.
Other laureates prefer to deliver a highly specialized talk on the latest developments of an esoteric
theory which they believe must have impressed the
jury, something like "Pivoting rules on an hypergeometric torus with extensions to n-dimensional chessboards for applications in human resource management" by Malcolm S. Goldilock Sr., Dr. gloriolae
causa mult in Theoretical Folklore.
Such presentations are usually deeply appreciated
by a fascinated audience (Fig. 3) whose only concern
is to pick up a few impressive keywords which they
will be able to use in their next talks or, even better,
in their travel reports when going back home.
The audience would in addition appreciate it even
more if, in addition, all these essential keywords
could be placed as early as possible in the talk, so
that the public could get back either to sleep or to the
classical urgent and nontrivial activity which takes
Fig. 3. A fascinated audience.
place during every opening session: reading the conference program, preparing the schedule of the next
days, checking if their talk is located in a rather
central auditorium and not scheduled as the first
morning presentation following the banquet.
Ladies and gentlemen, I am not sure I will follow
the rules, but nevertheless I do hope that you will be
able to use the time of this opening session to
Fig. 2. Climbingto the Olympusof Science.
Fig. 4. Are unimodular hypergraphs more important than a faroily?
D. de Werra / European Journal of'Operational Research 99 (1997) 207-219
construct your optimal attendance program for the
next days.
My first thanks are for my wife Brigitte who had
the most essential contribution to this award: asking
periodically whether unimodular hypergraphs were
more important than a family (Fig. 4) or whether
balancing an edge coloring was a more applied
activity than living the unique life we are given,
Without her, the medal would simply have gone,..
elsewhere !
I would like to take this opportunity to also thank
the jury (Fig. 5): now for a little while my wife will
be slightly more inclined to believe that after all I
may really have been trying to do some OR during
almost all the weekends and the evenings of the last
25 years (not including the hours spent in preparing
this talk).
The next thanks go to Jean-Pierre Brans who
invented more instruments than any engineer in the
world; among his most popular discoveries, the gold
medal is a famous one. It has been around for as
many years as Greek Gods and Prometheus, :So that
people already talk about the EURO old medal.
1. About the choice of the jury
But now let me confess that I am really puzzled
by the decision of the jury and I wish to start by
congratulating the president, Graham Rand, and the
members for their unusual sense of humor. It is
indeed very amusing to see what their choice was,
when you realize the infinity of reasons they had to
choose another laureate.
Fig. 5. Thanking the jury.
209
Among these reasons, let me just mention a few:
First, I thought that being a former EURO President would have kept me far enough from the list of
candidates; moreover, as a Presi,lent who did not
invent any new instrument for EURO, I should have
been an ideal non-nominee.
Besides this, I am not a member of the multicriteria chapel: dealing with one criterion or even no
criterion at all is already a difficult problem which I
can solve only in a few very special cases.
In addition, neither a EURO Summer Institute nor
a Miniconference has ever been organized in my
country; this is not unexpected since Switzerland is
not a member yet of the European Union. By the
way why should a European award go to a nonEuropean nation?
What then was in the mind of the jury? Modestly,
I have to tell you that my unique - and hence
trivially most important - contribution to EURO was
to educate the last two treasurers of EURO: indeed,
Jean Bovet and Marino Widmer got their Ph.D's in
Lausanne, but it was in OR. So I have again committed a mistake b y forgetting to teach them some
accounting, But EURO will survive.
At this stage you certainly wonder whether the 95
Gold Medal was awarded erroneously; at least so do
I.
But I thought I finally found a reason: up to now I
have been able to attend all EURO Conferences and
in particular all opening sessions; alas very soon I
realized that at least two additional members of
EURO were in the same situation. All of us intend to
participate in the next conferences; knowing that
EURO waives the registration fees of the laureates,
was it really clever from the jury to choose a medallist who w o u l d otherwise have continued contribut=
ing to the wealth of EURO by paying his registration
fees?
In conclusion, I see absolutely no good reason for
being on the stage today, except that O R has always
been a deep enjoyment for me (Fig. 6).
I would like: to express my gratitude to all those people and institutions - who have helped me along
this path: first at the Ecole Polytechnique F~d6rale
de Lausanne, Professor Charles Blanc who suggested
to the physicist I was to start a Ph.D in OR and to
have a look at these strange animals called graphs
which might even be useful for scheduling purposes;
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D. de Werra l/European Journal o f Operational Research 99 (1997) 207-219
Fig. 6. OR is a deep enjoyment.
then at the University of Waterloo (Canada) to the
late Professor Don Clough whose friendship and
encouragements were crucial in persuading me that
research and teaching could be fun.
Permanently divided between theoretical problems and applications, I am deeplyindebted to Peter
Hammer who convinced me of two things:
(a) Not only pure mathematics, but also applied
mathematics can be beautiful; furthermore heuristics
can be clean procedures.
(b) Mathematical questions should be raised anytime (but Boolean problems preferably during the
nigh0.
If OR has really been an intense pleasure, it is
mainly due to the huge clique of good friends between whom years have introduced a multitude of
colorful edges.
My gratitude goes in particular to Bemard Roy
through whom I discovered that culture and humanism were the basic ingredients in the process of
changing OR from a collection of techniques into an
integrated decision aid science.
In addition, the Poznan triangle consisting of Jacek
Blazewicz, Roman Slowinski and Jan Weglarz deeply
impressed me with their unlimited imagination capacity for inventing day after day variations of
scheduling models which all turned out afterwards to
be useful.
Jakob Krarup contributed to convince me that
co-writing may by and large be a particular pleasure
[12].
Paolo Toth, before becoming a successful EURO
president, has been a stimulating friend with whom
we worked on a variation of the famous marriage
problem, which we did not dare to call the divorce
problem although it contained a kind of s e p a r a t i o n
t h e o r e m [13].
Pierre Hansen, one of the first EURO laureates,
besides being a personification of multidisciplinarity,
has always been a stimulator of scientific curiosity.
To him and to Fred Glover our community owes the
bases of what specialists call the TSP, i.e., the Tabu
Search Procedure [9,10].
I would like to thank all of them without whom
OR would not have been the same. Many of them
have been nice enough to invite me to be a co-author
and I wish I could tell each of them how much I
appreciated these opportunities to work together.
Thanks to them I have realized that OR could only
be teamwork (Fig. 7).
I do not know if our field is more inclined to
create links between researchers than other sciences;
I just observe that a few years ago almost all of us
had initially different backgrounds. OR was a new
field to us; so interdisciplinarity was more than a
word to many of us: it was an initial condition. I am
convinced that it has brought substantial benefits in
our scientific developments and in our efforts towards mutual understanding.
It was quite fortunate that our science could start
on such bases: in other areas like nanotechnology the
lack of initial interdisciplinarity constitutes a massive
obstacle to their development, which may cause a
dangerous delay.
Fig. 7. OR is teamwork.
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
Fig. 8. Manystudents influence their teachers.
Another essential ingredient of our relations was
rumor. In fact etymologically humor is human and I
eeould add that it is the only reasonable scientific
attitude: humor is often a way of making a step
backward and looking with some distance at what
we are doing, asking whether it has some importance
or relevance. I do hope that the OR makers and users
will always be serious enough to include some humor in their scientific activities.
An OR maker without humor is like a university
without students: it looks empty. It is appropriate for
me to thank the many students who have extensively
influenced their former teacher or supervisor (Fig.
8); the job of a student is well defined: it consists in
asking as often as possible good questions, i.e.,
questions to which you have no answer. Is this not
essential for us who are often accused of having
many answers but sometimes no questions?, or many
solutions to no problems? A Dar~vinian philosopher
used to say: It is as wrong for an OR maker to invent
a problem as it would be in biology for an existing
organ to create the necessity.
211
In particular I would like to thank Alain Hertz and
Marino Widmer who have raised so many stimulating questions when they were students that the only
way out for them was to become professors.
More generally let me congratulate all the former
members of the OR group at the Ecole Polytechnique F6d&ale de Lausanne: they asked many questions with enthusiasm, solved some of them with
intelligence and left the others with a deep wisdom
for their successors. After all, this medal is theirs.
Now that T have finally reached the end of these
preliminaries, you may still expect me to give you a
philosophical view of OR and its future. The exercise is perilous, as some people may have realized
earlier.
Remember for instance that in 1933 Lord Rutherford, Nobel Prize winner, claimed that "energy produced by atomic fusion is really not interesting;
whoever expects to obtain a source of power through
a transformation of atoms is a crank".
In 1957, the inventor of the Audion tube, Dr. Lee
De Forest, stated that man would never reach the
moon, whatever the future scientific developments
would be.
More recently, in 1977, Ken Olsen of Digital
Equipment was saying that "there is no reason why
everybody would have a computer at home".
I hope you will now understand why I prefer to
leave this exciting game to some former EURO
Presidents at the celebration of the 20th anniversary
of the Association.
Let me also immediately make it clear that I will
n o t be able to give you in a smart wording the
definition of our field which you may have been
looking for in the last twenty years (Fig. 9). Realizing how frustrated you may be, I would now simply
like to report on some experiments which are related
to the connections between OR and engineering.
The first observation I would like to underline is
that the recognition of OR among the engineering
community has considerably spread in the last years;
our association may be partially responsible for this.
There are several signs of this evolution. Let me just
remind y o u of some.
Talking about the new curricula for engineers, we
were recently discussing the title of some courses
related to OR. Someone suggested to call it 'Discrete
Mathematics'; but then a professor of engineering
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D. de Werra / European Journal of Operational Research 99 (1997) 207-219
Fig. 9. "OR is what OR makers are producing!".
proposed this: "call it OR; at least we know what it
is!". They all approved of the idea. I wish all OR
makers would be as categorial as this professor of
engineering in their perception of our field.
In 1988 the CONDOR Committee (Committee On
the Next Decade in OR) was expressing its confidence that the next decade could be the decade of
OR [3]. But this decade is apparently not ours:
President Bush stated a few years ago that we were
entering the decade of the Brain. I sincerely hope
that these dedications are not incompatible.
resistive circuits. The problem could finally be expressed in terms of finding an orientation of a network with some specific properties.
The surprise for the engineers was to discover that
discrete optimization concepts did arise in some
apparently continuous engineering problems where
only the values of the current in the branches were
concerned. With Martin Hasler and some other colleagues we could develop a model based on matroid
intersection [11]. The engineers started then to be
really interested in discrete structures.
It is also a merit of OR to have contributed to
developing some areas of pure mathematics. The
case of graph theory is an illuminating example:
regarded from the early 18th century on as a collection of strange objects (Fig. 10) and a source of
easy-to-formulate but not-so-easy-to.solve combinatorial problems, graph theory now comprises a solid
theoretical foundation in conjunction with a variety
of algorithmic tools. It is well known that most of
the theoretical developments in graph theory were
motivated by applications.
2. OR is a pure science
After a few years of teaching experience, my
belief is that OR is a basic science for engineers in
the same way as mathematics and physics; as such, it
should be present in all curricula, but it would not be
wise to develop programs of education centered exclusively on OR: the main virtue of this science is to
present an excellent opportunity of training all engineering students to modeling; in this perspective, it is
a complementary science to physics.
Besides this, OR also is a privileged binocular
through which illuminating and motivating glimpses
to pure and aesthetic mathematical structures may be
given to a student in engineering, Teachers should
take advantage of this whenever an opportunity
arises.
A few years ago we had a chance to have contacts
with electrical engineers who were studying the existence and the uniqueness of solutions in nonlinear
Fig. 10. A collectionof strange objects.
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
~
~.~:~,~ . ~
i~~¸
~o~
~~
~
Fig. 11. Even things which look dead may be useful to many.
From a scientific curiosity it has grown not only
into a basic modeling tool but into an efficient
solution method for many problems of combinatorial
flavor and to an exciting field of exploration for
theoreticians.
But in addition there are striking examples where
graph theory - developed by OR makers - has
offered a solution to unsolved pure mathematical
problems. Such a situation occurred for instance in
the study of an optimal stopping problem for a
so-called two-parameter process in probability theory: suppose one would like to determine which of
two medical treatments is the most effective for a
given illness. As each patient arrives, we have to
decide which treatment to give; Two parameters
indicate the numbers of patients who have received
the first and the second treatment, respectively.
The problem consists in determining an optimal
stopping rule which weighs the cost of further testing
against the value of acquiring further information.
It turned out that with Robert Dalang and Les
Trotter, we could give a good description of such a
two-parameter optimal stopping problem [5] and derive its properties by using arguments from the theory of perfect graphs initiated by Claude Berge [1].
The major consequence of this research was that
pure and continuous mathematicians started to realize that discrete optimization (considered as a part of
OR) was more than 'breakfast mathematics' but
could also be considered as a respectable and even
useful field of research. OR is not a prefabricated
213
house; there are still many bricks to discover and an
infinity of trails to investigate.
Along the same line, simulation is an area which
has been developed within OR and which is now
widely used in all kinds of situations where no other
approach may be chosen. Numerical simulation programs are indeed run daily by applied mathematicians and by engineers. I t has now become a standard technique and no one associates it with OR any
more. Even if no none talks about these techniques
which may look dead, they are useful to many...
(Fig. 11).
3. O R is an o p e n science
Interdisciplinarity and transdisciplinarity (Fig. 12)
have been intimately involved in the development of
most sciences. For instance, the idea that the living
cells might contain a genetic code to be discovered
came not from biologists but from computer scientists. In our case we observe the same phenomenon:
Fig. 12. The practice of multidisciplinarity.
214
19. de Werra / European Journal of Operational Research 99 (1997) 207-219
the theory of network flows was obviously inspired
from electrical or hydraulic analogies. Simulated annealing is another example where OR has progressed
by integrating ideas from other fields; tabu search
grew from artificial intelligence. Many more examples could be enumerated.
For this reason, as a basic and living science, OR
will continue its development along promising tracks
provided it is allowed to breathe in fresh air and to
get some inspiration from outside. This is why the
methodology of our field should still benefit in the
future from the contribution of various researchers
with different backgrounds. An isolated OR would
be a dead science; we should recognize that people
from other fields are the best for bringing us the
originality needed to stimulate new areas of development.
4. O R relies on basic sciences and on life sciences
In the past, the activities of engineers had their
scientific foundations essentially in classical sciences: physics, mechanics and chemistry among others.
The developments of these areas in conjunction
with the availability of computing facilities have
enabled engineering to reach in many areas a high
scientific level and thereby to attack many problems
which earlier seemed untractable; it was a real change
of scale in the domain of action.
A new field of inspiration is now emerging: the
life sciences in general (Fig. 13). Nature has been
providing for millions of years a variety of systems
which are able to reproduce themselves, to survive in
hostile environments, to repair themselves, and to
adapt themselves to variations of the surrounding
world.
Could the engineering sciences benefit from such
examples? There is no doubt they can. For instance,
artificial neural networks have contributed to spreading new ideas about computing. Biotechnology and
more generally bioengineering is becoming a well
established research domain; furthermore many engineering schools are introducing compulsory courses
in the life sciences. Artificial life is a growing field
which provides many exciting research avenues to an
army of scientists [7].
Fig. 13. A modern view of the life sciences.
On this planet all forms of life involve the same
mechanisms under the control of the protein and
DNA-templating machinery. It is not at all clear that
this is the only possible basis for life. It is easy to
conceive of other forms of life in different media
with different reproduction and development mechanisms. As an example a computer virus is an artificial living organism which can reproduce itself and
evolve. The study of other life forms will undoubtedly provide some inspiration for our sciences and
broaden our understanding of the basic principles of
life.
Will they be disappointed, those who have shown
such an enthusiasm for these life sciences, which by
essence seem to have a level of complexity much
higher than the classical engineering sciences? The
future will bring an answer; but we may hope that
the computing systems which are now available will
allow us to explore with a systematic aggressiveness
these virginal fields.
At this point we should realize that the life sciences are not just a fashion; they have been around
for millions of years and there is some evidence that
they will remain for some time.
Is OR concerned with these developments? Obviously OR has been reached by this roaring wave: the
genetic methods which were a few years ago considered by specialists of optimization as a classroom
game are now on the verge of becoming a powerful
heuristic procedure [6]: imitating a reproduction process in which offsprings inherit some characteristics
of their parents, these methods, which also include
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
mutation processes and take fitness into account for
natural selection, produce populations of good solutions in reasonable computing times.
Another research direction which seems worthy of
interest is the development of the ant algorithms [2]:
H o w can a population of ants (each one having
limited computing facilities) cooperate in constructing a collective nest or in finding optimal paths to a
food source? H o w can a collective behavior emerge
from a population of elementary computing units? It
turns out that a simple model - imitating the trace of
pheromone left by ants along the tracks followed can produce the required cooperative behaviour. Such
a technique may in particular be applied for coloring
the nodes of a graph with as few colors as possible: a
population of ants is thrown into the graph and in a
few iterations a coloring is produced. The first results are encouraging but more can be done.
The traveling salesperson problem is also a field
of action for ants. At this stage all this may be
considered as a nice intellectual game, but it may be
more: remember that we had in the past many examples of techniques and approaches which started as a
game and at the end provided either extremely efficient numerical methods or ideas for developing new
procedures... The case of Boolean algebra is famous:
from an elegant algebraic game it became a fundamental tool for computer science.
We can hope the best for a civilization which
substitutes ant systems for expert systems...
Is this not the first occurrence of a weak duality
theorem? In which case we may respectfully regard
our field as a mature science...
In front of such an audience of specialists in OR
(Fig. 14), I feel ashamed to express elementary and
trivial ideas which all of you certainly had years ago.
My first aim is simply to try to communicate m y
enthusiasm for the domain and hopefully encourage
at least one or two members of the audience to
continue research in the area.
6. O R is an art
Up to now, I have been attempting to show that
OR shares many characteristics of a basic science
and that it has been enriched with contacts with the
outside world. Some of us believe it is an art and I
agree with this statement for some reason which may
not be quite classical.
An artist is indeed a person who, being more
sensitive than average people, sees and guesses things
which others may not even notice consciously, and is
able to express them in an aesthetic way. He is a
person who establishes connections between the outside universe and an inside world and who can
express them.
5. O R is a n a t u r a l science
After all, what is the meaning of the connection
between OR and populations of ants? It may simply
show that optimization occurs in nature, so OR is in
this sense a natural science. It will benefit from the
observation of nature, from the identification of :optimization processes and from their adaptation to feasible optimization techniques. Are these not precisely
the steps o f basic scientific research?
By the way, optimization is in fact more than
natural, it is also supernatural:
"Verily I say unto you, Among them that are
born of women there hath not risen a greater than
John the Baptist: notwithstanding he that is the least
in the kingdom of heaven is greater than h e " (Matthew XI, 11).
215
Fig. 14. An audience of specialists.
216
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
As far as OR is concerned, it seems that noticing
links between different domains, establishing connections and trying to exploit the knowledge of one
domain to interpret and understand another field, is a
fruitful intellectual process which generally leads to
scientific progress. Is it not the classical way to
stimulate research and discovery in other sciences as
well?
Through its tumultuous historical developments,
OR has grown into a body of knowledge which
consists of heterogeneous pieces ranging from microeconomics to stochastic processes through combinatorial optimization. It therefore provides many opportunities for researchers to detect some hidden
links between various pieces and to cross-fertilize
these areas by bringing to one of these fields ideas
stemming from the others.
Without claiming any fundamental discovery, we
had the opportunity with N.V.R. Mahadev and Ph.
Solot to develop links between graph theory - more
precisely graph coloring - and machine scheduling
[14,15]; trying to establish connections between these
areas has been an exciting challenge which as
byproducts has given extensions of chromatic models on the one hand and tractable generalisations of
scheduling models on the other hand.
In a similar vein, with Alan Hoffman, N.V.R.
Mahadev and Uri Peled, by exploiting a mathematical programming formulation of a chromatic
scheduling problem we were able to derive some
results on restricted colorings; these provide elegant
scheduling algorithms and certificates of non-colorability which may be used for tackling timetabling
problems with unavailability constraints [16].
On an analogous basis, recent experiments have
shown that combinations of algorithms of different
spirit could give very reliable procedures which have
nothing in common with their ingredients. An illustration is provided by a special case of evolutionary
algorithm, the genetic algorithm, where at each step
a population of solutions is present, as we have seen.
Taking its roots in the life sciences, such a technique
repeatedly uses a reproduction routine choosing parents with a high fitness, a crossover operation generating offspring and a mutation mechanism introducing some diversity (a necessary piece of fantasy) in
the population.
Besides this, iterative algorithms move from one
Genetic Algorithms
I ,
Iterative Procedures
Reproduction
I Descent Methods J
Crossover
I TabuSearohI
Mutation
Hybrid Algorithms
J
Reproduction
Descent Methods
Crossover
Crossover
Tabu Search
Mutation
Evolutionary tabu search
Evolutionary descent algorithm
Fig. 15. Hybrid algorithms.
solution to the next until a stopping criterion is met;
here the population consists of one solution. Descent
methods and tabu search are examples of these iterafive algorithms.
It turns out that combining in a clever way a
genetic procedure with a descent technique gives as
offspring some hybrid algorithms (Fig. 15); we have
now entered the domain of metagenetic science.
These first steps have already suggested new ideas
for graph coloring in particular.
Among the most promising approaches, the evolutionary tabu search where mutation is replaced by a
tabu search procedure was suggested by Fleurent and
Ferland [8]; moreover an evolutionary descent technique was designed by Costa, Hertz and Dubuis by
replacing the reproduction phase by a descent method
[4].
I am convinced that there is still substantial
progress to be made with such 'artistic' approaches.
" L ' a r t na~t de lntte, vit de contrainte et meurt de
libertd" ( " A r t arises from struggle, lives from constraints and dies from freedom").
Andr6 Gide was certainly thinking not only of art
in general, but of OR as well, realizing that it was an
art: OR was indeed born from the struggles of the
second world war. As an applied science, it has
permanently been under pressure in its development:
urgent problems had to be solved; it was a matter of
survival. Even if such a pressure might have disturbed the serenity of its development, our field has
to be thankful for this stimulation, without which
D. de Werra / European Journal of Operational Research 99 (1997)207-219
much less would have happened; this occurred again
very frequently in recent years.
In flexible manufacturing systems and in robotics
for instance the technology came first and gave birth
to highly complicated systems which happened to be
not so trivial to operate. This was the challenge
which motivated the explosion of research papers
dealing with these new types of scheduling problems
which turned out to be exciting to solve, like cyclic
scheduling, or scheduling jobs with bounded processing times, or taking into account the presence of an
automatic guided vehicle.
Telecommunications and communication systems
have caused a similar situation and there is still
much progress to be expected for our field in these
technologies.
In general the OR science has taken great advantage from these emerging developments.
As an applied science, it may not have the freedom of a pure scientific domain: while a pure scientist can choose his path through difficulties, moving
around obstacles and reaching a discovery which
may be far from his initial views, an OR maker often
has n o freedom to choose his goal; he is like an
engineer who knows exactly what he has to solve.
In that sense, Andr6 Gide may still be right: OR
as such would die from too much freedom.
However, we should there again accept an inspiration from the life sciences.
A living organism produces naturally normal cells
which are adapted to the present environment; but it
217
also generates a small percentage of extravagant
cells which are out of the norm. These are ready to
help the organism to adapt to possible alterations of
the surrounding medium and to survive; they are in
some sense exploring other possibilities of life.
University authorities apply these biological rules
by accepting and even encouraging, by virtue of the
academic freedom principle, some people to be nontraditional in their research and teaching activities.
For OR too, some freedom is needed for survival:
a few special cells are necessary and basic research
should sometimes be encouraged even if the immediate goal is not obvious. Such an open attitude is to
some extent justified by the first principle of OR
dynamics: go first, the applications will follow.
Besides being at the same time a science and an
art, what else could we require from OR?
7. OR does miracles
The ultimate achievement of a perfect science like
ours would be to produce miracles. They did happen,
and more than once.
First, is it not a miracle that so many colleagues
all over Europe and in the EURO Association became excellent friends? This has been the best stimulation for my research and I did really enjoy it. There
is no greater pleasure than working m a community
where curiosity is the motivation to work and scientific competence the only hierarchy (Fig. 16).
Second, I have seen another miracle of our science: it has succeeded where other fields would have
dramatically failed and this is one more reason for
me to be grateful: OR was powerful enough to get a
color-b]in(i person, as I am, really excited about
colorings.
8. Conclusion
Ladies and gentlemen, as announced, I have not
:lear definition of our field. I
vince you that it is a basic
est education to modeling; it
to thrive. It is a ~atalyst for
ciences (like pure mathematitS).
Fig. 16. The great pleasure of working in a scientific community.
It i s well known that engineering among other
fields offers many possibilities of applications to
218
D. de Werra / European Journal of Operational Research 99 (1997) 207-219
OR; on the other hand, many areas (like engineering
in general, or the life sciences) provide a permanently renewed source of inspiration for new
methodologies in OR.
But one of its main contributions is to have given
to discrete and to applied mathematics a sufficient
degree of respectability in the scientific community.
The frontier between pure and applied mathematics
is nowadays vanishing; in a similar way to the
globalization we observe in the world economy, we
will soon reach a stage where pure and applied
mathematics will be considered together as a small
subset of a global science, which will perhaps be
called OR.
Finally, I would like to dedicate this medal, which
was deserved by my colleague researchers at EPFL
and in many other places, to my father who deceased
a month ago and who, as an obstetrician, was an
admirer of life sciences. I will remember from him
that a necessary key to success consists of a reason-
able amount of work, a sufficient quantity of doubt
and as much humor as displayed by a EURO jury.
Ladies and gentlemen, in French, OR means gold.
We are so tempted to say that OR is gold for all of
us, but we should not forget that it is not all in our
lives. " T o u t ce qui brille n'est pas de l ' o r " : " E v e r y thing that shines is not necessarily O R " , might say a
famous proverb. There are important issues which
are much beyond OR. Our education in the field may
however invite us quite naturally to raise the only
essential question: " A f t e r all, what is my objective
function?" (Fig. 17).
Acknowledgements
Most figures are borrowed from the work of
Benjamin Rabier. Figs. 12, 14 and 17: G6d6on, roi
de Matapa (Gamier, Paris, 1932). Fig. 2: Gdd~on
dans la forSt (Gamier, Paris, 1977). Figs. 3 and 8:
G6d~on, chef de brigands (Gamier, Paris, 1978).
Figs. 1, 4 and 16: G6ddon, grand Manitou (Gamier,
Paris, 1949). Fig. 10: G6d6on se marie (Gamier,
Paris, 1950). Fig. 11: Les Fables de la Fontaine,
tome II, Benjamin Rabier (Tallandier, Paris, 1906).
All above-mentioned figures are copyright © ProLitteris, Ztirich, 1995.
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Fig. 17. What is my objective function?
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