An agent based Model of Reality in a Cadastre
"Land, after all, is the ultimate resource from which all wealth comes." [3,p.21]
foundation for human settlement is the land without which human life
would be impossible. Its value and importance is therefore extremely
high. Land cannot be increased, it is a limited resource and an
important factor of production. Much effort is invested into the
management of land. Cadastral systems are developed all over the world
for this purpose. Consequently a major demand for effective and
efficient organization of these systems exists .
for efficient cadastral systems is the understanding of the reality
which the system should correctly represent. It is not sufficient to
investigate only the cadastral registry with its content and input and
output operations. The registration process in the cadastral registry
captures only a part of reality. The complexity of phenomena involved
makes it necessary to widen the scope to the more general view of
reality in a cadastre that comprises the cadastral registry as well as
people acting in the real world. This allows to represent a more
comprehensive view on the cadastral domain.
Reality in a cadastre
is determined by a broad variety of phenomena. On one side there are
physical phenomena, for instance, land pieces and human being acting on
land. On the other side there are social constructs, for instance,
ownership, legal persons and rights. These social constructs influence
the behaviour of people in physical reality and play thus a crucial role
for the representation. A model representing reality in a cadastre has
to be a model of social reality.
Much research has been done to
understand physical and social reality around us. There is only one
reality and the question arises how they are connected. How is the fact
that a person is the owner of a parcel based on the physical properties
of human beings and parts of the earth surface? The improvement of the
understanding of the small part of reality, namely reality in a
cadastre, contributes to our understanding of reality in general.
issue in the analysis of social reality is the complexity of the
involved phenomena and the difficulty to extract components small enough
to construct models. Cadastre is an appropriate field to explore social
reality because it is on on side a relatively separated part of reality
with limited influences from and to other parts of the real world. On
the other side the rules structuring social reality in a cadastre are to
a high degree known and represented in laws and thus the field is open
to an analysis.
There are tools necessary to support the
improvement of our understanding of reality and its consequences for the
construction of more efficient cadastral systems. Computational models
are appropriate for this purpose because they allow the simulation of
processes in reality. For instance a model representing reality in a
cadastre enables the simulation of the behaviour of a person violating
the legal rules and its consequences to the cadastral registry.
is advantageous to use a formal tool for the model of reality in a
cadastre, i.e. a formal specification language with clear semantics.
This allows to represent the domain in a clear and unambiguous way and
helps to avoid misunderstandings. The formal model should be executable
because this enables the construction of computational models.
Computational models based on a formal executable specification have
advantages compared with models not based on a formal foundation. A
model based on a formal specification formally correct represents its
specification, i.e. it does the right things with respect to the
specification. This enables the testing of the model with appropriate
test cases to investigate its correspondence to the reality it
The key issue for the
analysis of reality in a cadastre is the understanding of the social
concepts involved. The question is how to represent social reality.
Formal models have advantages compared with non formal approaches. The
main research question of this thesis is therefore:
Is it possible to construct a formal, computational model of (social) reality in a cadastre?
reality in a cadastre is highly determined by institutional concepts
(e.g. ownership, parcel,...). In the model it is sufficient to represent
only institutional reality. The relevant institutional concepts are
defined in laws (especially the cadastral law). By the analysis of the
cadastral law it is possible to extract the rules constituting
institutional reality. Searle's theory on institutional reality 
introduces an approach dealing with institutional concepts and gives the
theoretical and philosophical background of this work. Social reality
in general and institutional reality in particular are determined by the
behaviour of human beings. Thus for the model a representation of human
intentions and behaviour is necessary. Agent theory [9,5,13] gives the
conceptual framework for this task. It allows formally representing
human intentions and behaviour necessary for the model of reality in a
cadastre by agents. The hypothesis of this thesis reads as follows:
formal, computational model of institutional reality represented in an
agent based framework represents the relevant aspects of reality in a
The basic approach of this thesis is
the construction of a formal and computational model of reality in a
cadastre. The correctness of the model will verified by agent based
simulation of appropriate and characteristic processes from the real
world in the constructed model.
The following tasks characterize the approach of this thesis:
on a sophisticated philosophical foundation with and analysis of the
domain in question (modeling of institutional reality in a cadastre).
Use of agents and agent theory as conceptual framework to represent the domain.
Use of an algebraic specification [7,4,6] as formal framework to represent the domain.
of the algebraic specification in the functional programming language
Haskell. [12,10,1] to reach a computational model.
Empirical validation of the model with appropriate case studies.
thesis applies Searle's theory of institutional reality to the analysis
of reality in a cadastre. The analysis results in a basic ontology of
reality in a cadastre. Based on this ontology a model will be developed
in an agent based framework. This model will be represented with a
Haskell specification. This specification allows agent based simulation
of processes in reality. To verify the correctness of the model two case
studies will be performed. One case study is the transfer of ownership
of a parcel between two persons and the second is a conflict regarding
land use and the resulting legal action and judgement execution.
Goal of the thesis.
general goal of this thesis is the investigation of the structure of
reality in a cadastre as part of social reality. It comprises the
development a computational model of this reality. Based on this model
expressible case studies will be developed that represent a
comprehensive part of phenomena determining reality in a cadastre. These
case studies are the transfer of ownership on a parcel and conflicts
regarding the use of a piece of land between the owner, the authorized
user of the land and an unauthorized user of the land. The conflict
leads to a legal action by the owner and a judgement execution to end
the unauthorized land use. The result of these case studies are
simulations of social processes in a cadastre.
applies theoretical results from the field of Philosophy and Artificial
Intelligence to the cadastral domain. It focuses on the Austrian
cadastral system  to achieve a more realistic formalization. It
concentrates on the legal part of the cadastre, omitting spatial issues
because the questions raised by the research question are mainly
situated in this field. On the philosophical and formal foundation
social processes will be simulated according to the cases studies.
of this work is to develop a content theory in opposition to a
mechanism theory . It is mostly interested in reality in the
cadastral domain and not so much in the representation mechanism. The
focus is directed to the analysis of reality and a conceptualization of
the phenomena influencing reality. I does not develop a formalism for
agent based simulation. It uses a representation mechanism to apply the
conceptual framework developed.
expected result of this thesis is that it is possible to construct a
model of reality in a cadastre that can be successfully validated with
the case studies. The development of a computational model in an
executable specification language allows the validation by testing the
specification. A realistic formalization will be achieved by the
orientation on the concrete Austrian system. It will be expected that
the analysis of reality in a cadastre leads to a general ontology of the
cadastral domain which is applicable to other legal systems. The agent
based framework to developed in this thesis will be extensible to larger
parts of the Austrian cadastral law as well as other legal domains
possibly from other legal systems. From the choice of the functional
programming language we expect a clear and understandable representation
that helps to avoid mistakes and support the expression of the ideas of
The scientific contribution of a formal model model
of reality in a cadastre has a practical and a theoretical dimension.
It improves the understanding of reality in a cadastre and supports the
construction of efficient cadastral systems on the practical side as
well as a more realistic view of the world around us on the theoretical
R. Bird and P. Wadler. Introduction to Functional Programming. Prentice Hall International, 1988.
Chandrasekaran, J. Josephson, and V. R. Benjamins. What are ontologies,
and why do we need them? IEEE Intelligent Systems, 14(1):20-26, 1999.
F. Dale and J. D. McLaughlin. Land Information Management, An
introduction with special reference to cadastral systems in Third World
countries. Oxford University Press, Oxford, 1989.
H.-D. Ehrlich, M. Gogolla, and U. W. Lipeck. Algebraisch Spezifikation abstrakter Datentypen. B.G.Teubner, Stuttgart, 1989.
J. Ferber. Multi-Agent Systems. An introduction to Distributed Artificial Intelligence. Addison-Wesley, 1999.
I. V. Horebeek and J. Levi. Algebraic Specification in Software Engineering. Springer-Verlag, 1989.
Loeckx, H.-D. Ehrlich, and M. Wolf. Specification of Abstract Data
Types. John Wiley and Sons, B.G. Teubner, Chichester, New York,
Brisbane, Toronto, Singapore, Stuttgart, Leipzig, 1996.
K.-H. Marent and G. Preisl. Grundbuchsrecht. Linde Verlag, Wien, 1994.
O'Hare and N. Jennnings, editors. Foundations of Distributed Artificial
Intelligence. Sixth-Generation Computer Technology Series. John Wiley
and Sons, Inc., 1996.
J. H. F. Paul Hudak, John Peterson. A gentle introduction to haskell. 1997.
J. Searle. The construction of social reality. The Free Press, New York, 1995.
S. Thompson. The Craft of Functional Programming. Addison-Wesley, 1996.
M. Wooldridge and N. R. Jennings. Intelligent agents: Theory and practice. Knowledge Engineering Review, 10(2), 1995.