engineering of markets and artifacts
TRANSCRIPT
Electronic Commerce Research and Applications 3 (2004) 369–380
www.elsevier.com/locate/ecra
Engineering of markets and artifacts
Eswaran Subrahmanian a,*, Sarosh N. Talukdar b,1
a ICES and Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USAb Electrical & Computer Engineering and ICES, Carnegie Mellon University, Pittsburgh, PA 15213, USA
Received 3 October 2003; received in revised form 4 June 2004; accepted 17 June 2004
Available online 23 July 2004
Abstract
In this paper, we continue the dialog started by Roth [The Economist as Engineer: Game theory, Experimentation,
and Computation as Tools for Design Economics, Fisher Schultz lecture, Econometrica 70 (2002) (4) 1341–1378]
between economics and engineering in the context of design of markets. We take the position that markets and engi-
neered artifacts are the products of a social process of design formulation. Our perspective is that designing of markets
and artifacts follow the same kind of problem formulation and solution testing process. Further, we show using two
case studies that the design of engineered artifacts and markets are often interdependent. In light of their similarities,
methodologies for modeling and testing using theoretical, analytical, computation and physical models in engineering
can inform the development of methods for testing in the design of markets. We also illustrate an example of devising a
test and results of its execution thorough the use of a simple computational model of an electric power market. We
conclude by summarizing the similarities between the designing of markets and artifacts and call for a continued dia-
logue between engineers and economists.
� 2004 Elsevier B.V. All rights reserved.
Keywords: Engineering design; Market design; Modeling; Testing; Methodologies
1. Introduction
A recent New York Times column by Hal Var-
ian headlined, ‘‘Avoiding the pitfalls when shifting
from science to engineering,’’ reviewed a paper by
1567-4223/$ - see front matter � 2004 Elsevier B.V. All rights reserv
doi:10.1016/j.elerap.2004.06.002
* Corresponding author. Tel.: +1-412-268-5221.
E-mail addresses: [email protected] (E. Subrahmanian), taluk-
[email protected] (S.N. Talukdar).1 Tel.: +1-412-268-8778
Alvin Roth entitled, ‘‘The Economist as an Engi-
neer’’ [19,27]. Why do we suddenly see economists,
purists in their claim to science, starting to see that
engineering is an integral part of economics? Is it a
startling return to often-forgotten Thorstein Veb-len�s view of economists as engineers of the price
system? Is it a renunciation of the claim that eco-
nomics is a pure science? Science without experi-
mentation is no science at all for all the
mathematical devices are not enough to guarantee
ed.
370 E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380
the validity of the theory if it is not tested in prac-
tice; it is here engineering becomes very important.
While these are fascinating questions, this paper
will focus on a much narrower question. This pa-
per takes as its starting point that the developmentand use of a market is as much a socially designed
mechanism as any other artifact [5]. We take up
this perspective – from the engineering side – in
what we hope will be a dialogue between econo-
mists and engineers about how the experience with
engineering design of artifacts can help inform the
discussion in economics� new focus on design of
markets. Here the lessons from testing from engi-neering become important. Perhaps more impor-
tantly, this debate between engineer and
economist will change the status of designing of
artifacts and markets themselves. While we are
not economists, but more students of design of
engineered artifacts, we want to view economics
with the lens of engineering design.
Our goal is to show that understanding designand engineering can create insightful approaches
to practical economics that have been brought to
fore by the emergence of computing in economics,
experimental economics and e-commerce
[14,17,26,29]. In these areas, the focus has shifted
from being solely on mathematical elegance to also
including as equally important, practical design,
simulation and creation of markets. This shift ineconomics from purely analytical to explore vari-
ous approaches to simulation through computing
has been profound. In this shift, Simon and Von-
Neumann have been most forceful in constructing
a vision of economics as simulated Cyborg Science
[14]. Of course, in this new context the issues of
methodology of research in design of markets have
raised questions that economists, until recently,have not asked themselves. We address some
of these issues by staking the claim that design of
markets has important similarities to design
of engineered artifacts. We further argue that mar-
kets and the nature of engineered artifacts are
more closely inter-related than most economists
tend to acknowledge and engineers dare to state
for fear of trespassing.The paper has five sections. The next section is
on the similarities between design of artifacts in
engineering and markets in economics. Section 3
addresses the interdependence between market
structure and structure of designed artifacts. Sec-
tion 4 then turns to methodologies in modeling
and testing for failures in engineering design and
its relationship to design economics. Section 5 isan example of devising a test for excessive profits
and testing it using a simple model of the electric
power market. Section 6 concludes the paper with
some discussions and conclusions on the relation-
ship between design of markets and artifacts.
2. Markets and artifacts
‘‘Economics is one of the Artificial Sciences’’
[21, p. 83].
Economics is part of the sciences of the artificialas Simon claims in his well-known paper on
bounded rationality and his book on the sciences
of the artificial [20,21]. The mechanisms of eco-
nomics, ‘‘markets (artifacts),’’ are designed to sus-
tain a particular set of desired behaviors (e.g., to
measure and keep time) through constraints on
behavior of the participants (functional/structural
parts) and on transactions (interactions) betweenthem. Determining the set of desired behaviors
and constraints on the artifact (market) is a social
process. In this sense, designing of markets is
something like designing engineered artifacts –
through the social interaction of actors in the for-
mulation of the market design problem and their
acceptance of the solution. We will elaborate on
this claim by first explaining what we mean by for-mulating a design problem and then use a charac-
terization of markets to show how the design of
markets is similar to the design of engineered
artifacts.
2.1. Formulating design problems (artifacts and
markets)
One wants a clock to provide the time without
failing every minute. One wants markets that lead
to innovation while not leading to the abuse of
market power. In designing a market, we want to
achieve a set of competing goals, which is exactly
what we want when we design any engineered arti-
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fact. The involved participants, i.e., those whose
interests are involved, set these goals and tests
for the acceptance of the artifact. We will now
elaborate this characterization design problem for-
mulation for engineered artifacts.In our characterization of a design formulation
[24], any design involves a collection of stakehold-
ers all with their own interests who come together
to formulate the design problem in terms of:
(a) Goals – Specification of behavioral and struc-
tural objectives and constraints
(b) Decision variables – Variables where choicesare to be made
(c) Design Space – The space of solutions derived
from the decision variables
(d) Tests – Agreements and metrology used in
testing the goals
(e) Starting points – Existing designed or natural
artifacts fulfilling a similar function as the
problem formulated.
From this viewpoint, we contend that the de-
sign of markets and artifacts are multi-goal (objec-
tives and constraints) problems with competing
and sometimes incommensurate interests. 2 In
both, we are concerned with efficient allocation
of resources, identifying appropriate trade-off
amongst objectives, identifying of constraints onthe structure and behavior, identifying tests that
would allow us to verify that constraints and
expressing behavioral parameters that embody
the different failures and performance criteria to
manage the negative effects and positive effects of
the artifact designed. In both cases, those involved
in the design and those affected have to perceive an
overall value in the artifact individually and collec-tively for it to be accepted.
To provide a starting point for the definition of
markets, we will use the definition of a market by
Guesnerie [9] rephrased by Callon [5],
2 This view does not imply that power relationships among
the stakeholders cannot bias the design and the outcome of
designs. However, we will see in Section 3, a case where the bias
of a set of the stakeholders can have profound impact on the
way both an engineered artifact and the market the stakehold-
ers participate in influencing each other.
‘‘a market is a co-ordination device in which:
(a) the agents pursue their own interests and to
this end perform economic calculations which
can be seen as an operation of maximizationor optimization;
(b) the agents generally have divergent interests
which lead them to engage in
(c) transactions which resolve the conflict by
defining a price.’’
In the elaboration of this definition of markets,
Callon uses prices/contract interchangeably, andwe shall do so as well. The reason for using a con-
tract is that, in the case of engineering design, price
is one of the many factors along with others such
as the use of standards and disciplinary and other
functional specifications. We will not explore these
here, other than to note that contracts are agree-
ments just as prices are.
Even though the above two characterizations(design of artifacts and markets) are not at same
level, the first can be used to elaborate the market
design model by identifying the elements that go in
to formulating this ‘‘co-ordination device’’ just as
one would with any artifact and the calculations
(tests) done by the calculative agencies to achieve
consensus. Resolution of conflict by the calculative
agencies (engineering design and/or markets) isthrough agreements on tests for achieving the
objectives and constraints agreed upon as the set
of goals. Even in the above definition of a market,
the word optimization is used. However, the opti-
mization process by the calculative agencies is lim-
ited by bounded rationality throughout the
process of the resolution and is tamed by the use
of models and methods to reduce time and/or thecosts of resolution. The resolution process in engi-
neering design is through the use of metrology,
analytical formalisms, simulations that embed the
learning and theorizing that is induced over the
experience of the designed artifact as it continu-
ously evolves responding to failures, technological
changes and spillovers [18].
Sustaining the evolution of an artifact in thepractice of engineered artifacts is by the develop-
ment of a range of calculative models and methods
for testing behavior as a means to tame the
372 E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380
limitations of bounded rationality. This kind of
adaptive behavior is not limited to design problem
formulations and engineered artifacts to overcome
bounded rationality. Arthur�s [1] work on the use
of a complex adaptive system metaphor for modelsof markets is that he could account for bounded
rationality by embedding agents with inductive
learning in the market models. These agents in-
clude mental models of the market that evolve
their discriminatory power to eliminate failures
to optimize their performance. The participants
in a market and the designers of the market are
both bounded rationally but both can adapt theirbehavior in light of experience either by optimizing
their interests given a market design or by refor-
mulating the market design problem to accommo-
date new failures and objective.
2.2. Failure in markets and artifact design
A theme that underlies the history of artifactdesign is managing and learning from failure
[16]. One of the most striking things that occurs
when we look at the history of the evolution of
markets and history of design is this uncanny com-
monality in the characterization of the failure
modes in their functioning in society. Economists
tend to call failures in behavior of markets nega-
tive externalities and the benefits positive external-ities. Engineers tend to label failures as any kind of
functional or behavioral breakdowns and to label
positive behavior of the artifact and its second or-
der effects as features or benefits. Often the second
order engineering benefits are economic positive
externalities (creation or facilitation of the func-
tioning of organizations or markets) from an arti-
fact design point of view. To set the context forcomparison, we will use Callon�s definition of mar-
ket failures [6, p. 247]:
‘‘Market failure occurs due to:
(a) Externalities – positive and negative.
(b) Asymmetry of information.
(c) Indivisibility of property rights.
To use a simple example, pollution is a negative
externality, while an increase in the tax base is a
positive externality. In the case of design, the
introduction of a car allowed for the dispersion
of the housing and commercial zones away from
each other while creating pollution and new forms
of accidents. The second kind of failure arising out
of asymmetry of information results in incompleteproblem formulations in artifact design as well as
in market design, often leading to seemingly desir-
able but poor solutions whose failures sometimes
are not visible, let alone testable.
It is not just engineering or economic processes
that are designed and that rely on managing fail-
ures. Simon also mentions the design of the consti-
tution of the US as driven by a desire to avoid theperceived failures of European experiences [20]. In
this case, one of the functional and structural as-
pects of the US Constitution, which often is over-
looked, is the three institution design to prevent
the kind of religious and other persecutions previ-
ously experienced in Europe.
The important lesson here is that a desire to
minimize recognized and anticipated failures whilemaximizing the benefits of all sorts is a fundamen-
tal driver of all human engineered design. How-
ever, one cannot identify and manage failures
without appropriate institutional rules and the de-
sign of appropriate metrology and tests to measure
the achievement of the goals. We will return to this
theme with respect to the use of tests in engineer-
ing and economics.
3. Market design affects artifact design and artifact
design affects market design
We will show two cases to illustrate these rela-
tionships. The first case is the history and emer-
gence of the electric power industry in the US[10]. The electric power industry in the US was
mainly a regulated monopoly until recently when
efforts to introduce markets in this industry began.
The original electric power industry in the US was
decentralized with even small buildings having
their own generators and with small companies
supplying power to small but often disconnected
sets of customers. However, some of the manufac-turers of large power plants felt that, by ensuring a
large number of customers for a regional supplier
of electricity, they could have a captive market
E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380 373
without much competition. At the time they
wanted to push this more centralized model of
production, they constituted less than half of the
US market. 3 However, as Mancur Olson pointed
out in The Logic of Collective Action, majorityinterests are often displaced by well-organized
minorities who more effectively promote their vi-
sion and interests [15]. In this case, the well-organ-
ized large manufacturers of large power plants
dominated, and large-scale centralized electricity
production became the norm. They did this
through a concerted effort with financial interests,
who were behind this centralized production mod-el, convincing government officials and the official
technical forums of the industry about the virtues
of a regulated ‘‘natural’’ monopoly. They con-
vinced key decision makers that it was beneficial
to everybody in this model. This approach lost fa-
vor in the 1980s when free marketers advocated
that markets would solve the problem of providing
power more efficiently. Some claim that a marketoverlaid on an old artifact design meant for a
monopolistic regulated structure was the cause of
the latest blackout in North America [4].
Market design in electric power is constrained
by the physical laws that govern the generation,
transmission, and consumption of electricity. The
supply has to be equal to the demand or else the sys-
tem will be prone to failures at a given geographicallocation at a given point in time. These physical
constraints impose themselves as constraints on
the market design. Clearly design formulation of
the power network and the associated markets have
to reflect this inter-dependence.
The second case is the case of computer indus-
try, where the formulation of problem as a mod-
ular decomposition of the designed artifactcreated its own markets and market structures.
Baldwin and Clark in their book on, ‘‘Design
Rules: Modularity in Design,’’ describe the evolu-
tion of the computer industry by pointing that the
modular design of IBM 360 was a departure from
its own earlier and other competitors vertically
and functionally integrated computers [2]. Modu-
larized design created not only opportunities for
3 [10, pp. 163–164].
IBM to address a larger varied market but also
created additional opportunities for creation of
and entry by firms into markets for modules. Sev-
eral manufacturers started to provide alternative
hardware components to IBM machines andthereby spawned a new industry and market that
turned out to be very beneficial to IBM at least
initially. In the case of the personal computers,
this modularity in design has further separated
hardware processors and components and the
software operating system and applications result-
ing in an industry structure with several suppliers
of components at least on the hardware side ofthe market.
The above two cases illustrate the inter-
dependence between design of artifacts and mar-
kets in the design, manufacture and operation of
the engineered artifact. As Simon argues in his pa-
per on role of organizations and markets, each of
these structures affords a certain economic advan-
tage in terms of reduction of complexities of thetransactions involved and the amount of exchange
of information in the effort to elicit a desired
behavior in context at the desired cost [22]. We
use and structure organizations and hierarchical
decompositions to suit specific purposes and con-
texts in the design of artifacts, similarly we have
to undertake design of markets for specific pur-
poses and contexts. For example, in the case ofmany engineered artifacts, buy or make decisions
involve trading off between buying a part/compo-
nent from the market or from an exclusive sup-
plier, or to internally make the part. The basis of
these decisions are on what a particular firm values
as its competitive advantage (organizational/tech-
nical) over what the market can produce for it to
achieve its goals. This tension may result in alter-nate hierarchical artifact decompositions based
on buy instead of make decision. The development
and use of appropriate standards by firms provides
them the opportunity to decide between buying
and manufacturing. Standards also play a key role
in how these markets develop.
The primary lesson from these examples is that
in designing markets for supply chains and othermarkets that are related to the design of engi-
neered artifacts, one has pay attention to the role
of design in determining where and what type of
Log (cost)
Log (cost)
CF
Analyt
Flight
Log
(er
ror)
Log
(er
ror)
WindTunnel
# of flightconditions Wind
Tunnel
CFD
(a)
(b)
Fig. 1. (a) Log of error vs. log of cost. (b) Log of # of test
conditions vs. log of cost.
374 E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380
markets are the most beneficial to operate. For
example, for standard nuts and bolts one could
use an appropriate existing e-commerce market
model to obtain the parts. However, in the case
of a brand new navigation system you may haveto have exclusive supplier(s). Here the type of mar-
ket one is engaging in is different in the nature and
length of transactions that go beyond price and
quantity measures sufficient in the case of nuts
and bolts markets.
With the understanding of the commonality and
interdependence between artifacts and markets, we
next take up the issue of how engineers deal withthe issues of testing for failures and overflows in
functional and structural behavior of the design
with modeling and experimentation serving as tests
verification and measurement. We then present the
relationship between the engineers approach with
that of design economists. In summary, as cau-
tioned by Varian, ‘‘an understanding and appreci-
ation of existing institutions, good theory, goodcomputational modeling and well designed experi-
ments are critical to a successful design’’ [27].
4. Methodological issues
4.1. Methodological experiences in designing engi-
neered artifacts
The design of aerodynamic shape for aircraft
provides an example of methodological ap-
proaches to testing a designed artifact with respect
to a specified formulation. We draw this example
from a case study of the design of Boeing 777
and the use of computing tools [3]. There are four
types of methods used in the designing of tests.They are (a) analytical, (b) simulation (CFD), (c)
scaled mock up (wind tunnel), and (d) flight tests.
In characterizing these methods and their use the
author presents two approximate graphs, (a) lo-
g(error) vs. log(cost) associated with the methods
and (b) other is of the cost of finding a point in
the design space by a method (Figs. 1(a) and (b)).
While there is a trade-off in costs and error forthese test methods, these tests do not measure ex-
actly the same design parameters or perform the
same tests. For example, wind tunnel testing will
allow for testing of additional effects with an over-
all modeling error while CFD will provide detailed
flow information difficult to obtain experimentally.Even the flight test with its most reliable predic-
tions will still have errors from anticipated condi-
tions. The measure of error is the deviation of
the predicted from the actual behavior. In spite
of advancements in computing, use of CFD mod-
els constitute a tiny fraction of all the aerodynamic
simulations done for an aircraft.
The above aircraft design example illustratesthat in artifact design models serve the purpose
of performing tests on the structural and behavi-
oral goals of the artifact. Similar to the four levels
of testing for just the aerodynamic behavior of the
aircraft, most artifacts have collections and levels
of tests that operate throughout the design proc-
ess. The cost curves for these types of tests vary
from discipline to discipline; nevertheless they dis-play similar trends and shapes. In the case of arti-
fact design, analytical and simulation models
provide only glimpses into the working of the arti-
fact. In practice, use of modeling and simulation
tools seems to be the most dominant in new de-
signs when there is a need to develop insights
[23]. On repetition of similar designs, data induced
design rules, heuristics, tend to dominate the de-sign methods, and computational models tend to
serve mainly as verification.
E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380 375
Informed changes to underlying assumptions in
these models and choices of design parameters re-
main critical in their evolution and utility. Engi-
neers would agree with the economists McAfee
and Milgrom [13] who in reporting on their expe-rience in the design of spectrum auction observe
that simple theoretical and analytical models pro-
vide insights and allow for creating tests that allow
for the exploration of trade-offs. Especially in the
case of complex engineered artifacts, given the
state of understanding and the complexity in creat-
ing and solving an all encompassing model of an
artifact would render the task be impossible. It ishere that specific theories for specific features of
an artifact with simple or few functional forms
are more helpful in developing insights and the
experiments (computational and otherwise) to test
for potential failures.
Engineers often use different levels of incommen-
surable models to test their design formulations
throughout the design process. Improvements inthese methods of testing come from advances in
several areas including theoretical and analytical
modeling, physical testing methods and computa-
tional modeling. New and updated models of the
structure and behavior of the artifact and creation
of corresponding tests challenge the formulation
regularly. This cycle of formulation and reformula-
tion takes place in an evolutionary manner as expe-rience in identification and testing of unanticipated
externalities and failures accumulate.
We have given a brief overview of methodolog-
ical approaches on how engineered artifacts are
tested for the goals of minimizing different types
of failures and maximizing expected performance
that are agreed upon in the design specification.
We contend that the approaches used by engineersare means to manage bounds on rationality that
pervade especially the design solution generation
and testing process.
4.2. The economist as an engineer
Alvin Roth coined the term Design Economics
in his paper on ‘‘The Economist as Engineer:Game Theory, Experimentation, and Computa-
tion as Tools for Design Economics’’ [19]. In this
paper, he argues the case for the use of simple
models in the design of markets, even in the pres-
ence of other complexities, that are augmented
with experience [19]. In making his case for Design
Economics with game theory as one of its theoret-
ical foundations, he illustrates using a simplemodel for auctions for medical interns akin to a ri-
gid beam model used for structural design of
bridges. He complicates the original model by
the use of more elaborate computational models
and the use of real experiments. The results from
these exercises augment the analytical and theoret-
ical to accommodate for complementarities and
other observed failures. These complications arisefrom the potential gaming behavior of the partici-
pants in the market as well as the change in the
strategic environment in which the market oper-
ates. Computational experiments allowed for
modeling different participant behaviors and mar-
ket rules where analytical models were too compli-
cated to solve. Computational models, for example
in Roth�s case, identify that an ‘‘undesirable condi-tion’’ unstable matching of residents to hospitals
does not occur in computer modeling when cou-
ples are considered while the theory predicts the
difficulty in finding a stable match given a set of
market rules. The main goal of computational
experimentation is to test for undesirable or desir-
able behavioral characteristics of the designed
market that lead to their failures or acceptance.As in engineering, design economics will have to
use different models provide different insights in
to the working of a specific market.
The identification of the need for multiple mod-
els of formulating and solving the market design
problem has grown in the literature on e-commerce
and distributed agents that use game theory.
Researchers on distributed agents [11], in evaluat-ing the utility of analytical game theory in the de-
sign of computational markets, are sober in their
assessment of its use for realistic problems. In a re-
cent paper, Wellman and his colleagues, exploring
bidding strategies for market based scheduling,
contend that the problem is not tractable analyti-
cally using game theory and that one may have to
use evolutionary search strategy (computationalmodeling) for specific contexts [28]. Adherents of
game theory and theories of complex adaptive sys-
tems use evolutionary algorithms to model and
376 E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380
simulate social systems such as markets. One can
answer the question of the realism and relevance
of such methods only by empirically testing them
for their relevance and usefulness [7] just as in the
case of CFD in aircraft design.Experiences in market design as reported by
their practitioners reinforce the experiences of
engineers in the design and development of arti-
facts [13,19]. Roth has laid out a program for de-
sign economics that includes computational
modeling, scaled human experiments, and actual
observations of market functioning that very much
have parallels in the engineering world [19]. Multi-level modeling and experimentation have been
used historically and is still very prevalent in the
engineered artifact world [17].
In making the argument that economists have
to pay attention to design for having a pragmatic
impact on society, Roth states the conditions for
the success of Design Economics,
‘‘. . . in the long term, the real test of our successwill be not merely how well we understand the gen-eral principles that govern economic interactions,but how well we can bring this knowledge to bearon practical questions of microeconomic engineer-ing. . . Just as chemical engineers are called uponnot merely to understand the principles that gov-ern chemical plants, but to design them, and justas physicians aim not merely to understand thebiological causes of disease, but their treatmentand prevention, a measure of the success of micro-economics will be the extent to which it becomesthe source of practical advice, solidly groundedin well tested theory, on designing the institutionsthrough which we interact with one another.’’ [19]
We conclude this section by asserting that meth-odological issues for testing the design of aircrafts
shown as an exemplar of engineered artifacts will
hold for design of markets as well.
5. An example in devising a test for a market design
using a simple model for power markets
In a recent paper, we proposed a test to identify
market designs that are prone to excess prices and
profits, whether from learning or capacity concen-
trations [25]. In devising a model for this test, we
use computational models of agents that are evolu-
tionary in terms of learning from experience, sim-
ilar to those in the literature on computational
economics, evolutionary economics and distrib-uted agents. Even without an elaborate model of
the electric power grid, a simple model of the mar-
ket reveals potential market failures in terms of
suppliers being able to learn to achieve monopolis-
tic prices under some demand conditions.
5.1. The problem
Since power systems contain few, if any, facili-
ties for the storage of electric energy, production
must track demand, instant by instant. This de-
mand is quasi-repetitive, meaning that in any long
sequence of consecutive time intervals, there are
sub-sequences of non-consecutive intervals in
which demand changes slowly, if at all. Let {Tn}
be such a sub-sequence, that is, a sequence suchthat the aggregate demand curve for interval Tn
is almost, if not exactly, the same as that for inter-
val Tn + 1. Consider an auction of electric energy
that is repeated for each of the intervals in {Tn}.
Let:
M be the number of suppliers (a supplier may
own several generating plants).
Pn = {pmn} be a set of problems, where pmn is amulti-objective optimization problem representing
the goals of, and constraints on, the mth supplier
in the nth interval. (Both short- and long-term
goals can be converted by techniques, such as the
rolling horizon, into a series of static optimization
problems, one for each interval [30].)
xmn be the final offer (to sell energy) made by
the mth supplier in the nth interval. More specifi-cally, xmn is a (3·J) matrix, each of whose col-
umns represents one of J generating plants. The
first row lists the quantities of energy (in MWh)
from the plants, the second row lists prices in $/
MWh, and the third row contains zeros and ones,
a zero indicating that the energy from the genera-
tor is being withheld, a one indicating that the en-
ergy is being offered for sale.Xn be the aggregate of the xmn for the nth inter-
val, that is Xn represents the supply curve in the
nth interval.
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U be the space of all possible values of Xn.
Sn = {Smn} be a set of strategies, where Smn is
the strategy used by the mth supplier to solve its
problem, pmn, and thereby, determine its final of-
fer, xmn, in the nth interval.Umn be the profit made by the mth supplier in
the nth time-interval.
Un = UmUmn be the total profits made by the
sellers in the nth time-interval.
Un be a model of the rest of the system from the
suppliers� viewpoint, that is, a model of the cus-
tomers, the market mechanism, and the network
for the delivery of electric energy.The triple: l = {Sn, Pn, Un} is a dynamic system
whose state variables include the offers and whose
outputs include the profits made by the suppliers.
The offers trace trajectories in the space, U. Thetrajectories converge, if at all, to one of the attrac-
tors of the dynamic system. (These attractors may
be points or more complicated features, such as
limit cycles.) To evaluate a dynamic system, onemust calculate its trajectories, find its attractors
and predict its outputs.
5.2. The importance of learning
One way to simulate trajectories is to pay human
subjects to devise {Sn}, the strategies on which the
trajectories depend. There are two disadvantagesto this approach. First, human subjects make deci-
sions relatively slowly; each experiment can take
hours, and even then, may not have lasted long en-
ough for the trajectory to reach an attractor. Sec-
ond, it is unlikely that any reasonable payments,
or other inducements, can cause the subjects to
faithfully adoptPn, the goals of the actual suppliers.
Our approach is to use software agents instead ofhuman subjects. The agents have automatic learn-
ing capabilities. (Learning is the process of convert-
ing experience and the results of experiments into
added competence.) If the demand is quasi-repeti-
tive and if the suppliers incur few if any penalties
for experimenting with their strategies, then learn-
ing can considerably increase profits. Even simple
evolutionary algorithms can be quite effective. Onesuch algorithm for determining xmn, the offer from
the mth supplier for the nth interval, is
1. Search the seller�s history for the K previ-
ous offers that resulted in the greatest
profits.
2. Apply crossover and mutation operators to
these previous offers to obtain a single offerfor the nth interval.
3. If the probability of mutation is non-zero,
decrease it before using the algorithm for the
next interval.
5.3. An example
Consider a uniform auction with 10 suppliers.
The auction is repeated for the intervals, T1, T2,
T3, . . . The demand in each interval is the same.
The offer by each supplier in each interval is al-
ways at cost, and has the form:
Quantity (MWh)
1 1 1 1 1 1 1 1 1 1Cost ($/MWh)
1 2 3 4 5 6 7 8 9 10Withholding
? ? ? ? ? ? ? ? ? ?These offers differ only in their third rows, that
is, only in the binary vectors that indicate which
blocks of energy are withheld. Let:Ucomp be the competitive clearing price obtained
when no energy is withheld.
Ulearn be the clearing price when each supplier
uses its own previous results and the evolutionary
learning algorithm to determine its withholdings.
Umax be the maximum possible clearing price
obtained when the sellers cooperate (collude) in
determining their withholdings.It was assumed that the effects of the delivery
network could be neglected so the customers could
be connected to the same node as all the suppliers.
Three types of demand were considered:
Constant: the aggregate demand in each interval
was constant at 60 MWh.
Linear: the aggregate demand in each interval
was made to vary linearly with price, specifically(Price in $)=120� (Quantity in MWh)
Nonlinear: the aggregate demand in each
interval was made to vary non-linearly with
price, specifically (Price in $)=360/(Quantity in
MWh)
378 E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380
The calculated clearing prices for these three
types of demand are given below.
Demand
Ucomp Ulearn UmaxConstant
6 10 10Linear
6 7 8Nonlinear
6 7 10Notice that with constant demand, the suppliers
can learn withholding strategies that produce thesame clearing price, as does collusion.
5.4. A test for excess profits
Indicators of a market�s potential for high prices
and excess profits, such as the Herfindahl–
Hirschman Index, Supply Margin Assessment,
and the Residual Supplier Index [31], reflect asym-metries in supplier capacities but do not take the
dynamics of markets, and particularly, the changes
producedby learning, into account. Inwhat follows,
we will define indices that include the effects of
capacity asymmetries, dynamics and learning. Let:
{Tn}, be a series of time intervals, each with the
same aggregate demand curve, D; Amax, be the
maximum possible value of the total profit the sup-pliers can make in a time interval by collusion or
any other means; Alearn, be the asymptotic value
of the total profits the suppliers can make in a time
interval when each supplier adjusts its offer-
strategy with evolutionary learning; Acomp, be the
total profit the suppliers will make in a time inter-
val if they offer all their energy at cost.
L ¼ ðAlearn � AcompÞ=ðAmax � AcompÞ:The larger the value of L, the greater the danger
of high prices and excess profits for demand D,
since real suppliers can be expected to learn at least
as effectively as an evolutionary algorithm.
This small experiment points out that even
using a simple model one can get insights into
the behavior of the sellers once we accountfor the salient characteristics of the market. As in
the experiment, the California experience shows
that suppliers did withhold power as a means to in-
crease prices and hence create undue profits. Using
these simple experiments as starting points, we are
currently examining different market rules, learn-
ing algorithms for buyers and sellers and expect
in the future to conduct joint human and compu-
tational agent experiments. We plan also to in-
clude models of the artifact (power systemsmodels) interconnected with the market model to
understand the effects of the physical constraints
and objectives of the network on the market trans-
actions that are realizable. Many in the field of
power markets have even called for comprehensive
simulation environments that integrate the physi-
cal systems with the market models for effective
training of personnel and management of thepower markets [8].
6. Discussions and conclusions
The important message of this paper is that for-
mulation of engineered artifact design problems
and market design problems are contextual socialprocesses involving multiple goals set by the ac-
tors. In the words of Roth, the importance viewing
economics from a design perspective would be the
following insight [19]:
‘‘The largest lesson in all this is that design isimportant because markets don�t always grow likeweeds – some of them are hothouse orchids. Timeand place have to be established, related goodsneed to be assembled, or related markets linkedso that complementarities can be handled, incen-tive problems have to be overcome, etc.’’
We illustrated that the artifact design and mar-
ket design problems are often inter-dependent and
evolve together making the context even more crit-
ical. Evolution may occur not just in the sense ofthe evolution of market rules and the evolution
of agents in them to create more efficient but more
computationally complex markets [14] but also in
the creation of new inter-linked sets of markets
and industry structures that evolve with the evolu-
tion of the design of the engineered artifact [2].
Failures in engineered artifacts often can be
attributed poor test specification or lack of useof new tests when a reformulation of the problem
is initiated to accommodate the changes in the
external conditions and overflows [13]. Successful
E. Subrahmanian, S.N. Talukdar / Electronic Commerce Research and Applications 3 (2004) 369–380 379
designs in both Roth�s conception of Design Eco-
nomics and in engineering design require that de-
sign outcomes not only have to perform in the
long run but also in the short run. To accommo-
date this form of endurance of the designed arti-fact and its different facets of behavior, use of
multiple modeling and testing mechanisms drawn
from different disciplines are critical to the toolbox
available to both engineers and economists for
contextualizing their designs.
Computing, theories of automata and game
theory have provided a way to characterize mar-
kets and create experimental test beds as in engi-neering. The computational toolboxes for
designers of specialized markets can be found in
the literature for trade networks [26], electricity
networks [26,8] and others. They are not substi-
tutes for real experiments or for a shared memory
of market designs and for validated models and
simulations. Without a shared memory of designs,
there will be no evolution and bounded rationalitywill prevent us from solving problems that are ever
more complex. Categorization and classifications,
of where what works and when, is an important
component of engineering science and design and
we expect that science of design economics will
be no different.
In order to create theories of markets automata,
Mirowski [14] makes a case for taxonomy of mar-kets and their applications. In the e-commerce
world, the paper on ‘‘Parameterization of Auction
Design Space,’’ by Wurman, Wellman and Walsh
is an attempt at creating a taxonomy of auction
mechanisms for automated auction negotiation
in the context of multi-dimensional auctions [29].
We agree with these assessments and efforts on
the need for taxonomy of markets. We believe intheir importance from historical experiences with
engineered artifacts [12]. Taxonomies of markets,
their models and experiences would go a long
way toward helping the design of more effective
and computationally more complex markets. A
well understood market design and its limitations
are always a good starting point for the next de-
sign even if the new design requires a reformula-tion. Good taxonomies help in searching for
good starting points. The contributions to the lit-
erature on market design are from computer scien-
tists, economists and others bringing their own
skills and perspectives. Observing this develop-
ment Roth says,
‘‘But if we want this knowledge to accumulate, ifwe want market design to be better informed andmore reliable in the future, we need to promote sci-entific literature in Design Economics’’ [19].
Maybe there will be a ‘‘Market Engineers
Handbook’’ someday.
In this paper, we have continued the dialogue
started by the economist Roth with design by
describing his vision of Design Economics. We be-lieve this dialog is important as the interconnec-
tions between engineering design and economics
can be strengthened by creating an awareness of
their shared interests in both communities. This
could lead to engineers and economists working
and learning from each other to formulate and
solve design problems.
Acknowledgements
We would like to thank Raghu Arunachalamfor inviting and urging us to write this paper,
and Ira Monarch, Robin King and Arthur Wester-
berg for discussions on this topic and comments.
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