Bretto 2013
Bretto 2013
Bretto 2013
ike in most fruitful mathematical theories, the theory of hypergraphs has many
L applications. Hypergraphs model many practical problems in many different
sciences. it makes very little time (20 years) that the theory of hypergraphs is used to
model situations in the applied sciences. We find this theory in psychology, genetics,
. . . but also in various human activities. Hypergraphs have shown their power as a
tool to understand problems in a wide variety of scientific field.
Moreover it well known now that hypergraph theory is a very useful tool to resolve
optimization problems such as scheduling problems, location problems and so on.
This chapter shows some possible uses of hypergraphs in Applied Sciences.
The graph theory is very useful in chemistry. The representation of molecular struc-
tures by graphs is widely used in computational chemistry. But the main drawback
of the graph theory is the lack of convenient tools to represent organometallic com-
pounds, benzenoid systems and so on.
A hypergraph H = (V, E) is a molecular hypergraph if it represents molecular
structure, where x ∈ V corresponds to an individual atom, hyperedges with degrees
greater than 2 correspond to polycentric bonds and hyperedges with deg(x) = 2
correspond to simple covalent bonds.
Hypergraphs appear to be more convenient to describe some chemical structures.
Hence the concept of molecular hypergraph may be seen as a generalization of the
concept of molecular graph. More informations can be found in [KS01] . Hypergraphs
have also shown their interest in biology [KHT09].
in parallel. Hence the data elements from a template should be stored in different
memory modules. So we define a hypergraph in the following way:
(a) A data is represented by a vertex.
(b) The hyperedges are the templates.
From this model and by using the properties of hypergraphs one can resolve various
problems such as the conflict-free access to data in parallel memory systems. Some
informations can be found in [HK00] .
where:
• V is a finite set of variables.
• D is a finite set of values which is called the domain of P.
• Each Ri (Si ) is a constraint.
– Si is an ordered list of n i variables, called the constraint scope.
– Ri is a relation over D of arity n i , called the constraint relation.
To a constraint satisfaction problem one can associate a hypergraph in the following
way:
(a) The vertices of the hypergraph are the variables of the problem.
(b) There is a hyperedge containing the vertices v1 , v2 , . . . , vt when there is some
constraint Ri (Si ) with scope Si = {v1 , v2 , . . . vt }.
(b) The set of hyperedges is the set of relations between these attributes.
We also find the theory of hypergraphs in data mining [HBC07] .
I : X ⊆ Zm → C ⊆ Zn,
where d is the distance on the grid and α is attribute on the image. The neighborhood
of x on the grid is denoted by Γβ (x). So each image can be associated to a hypergraph:
Hα, β = X, ({x} ∪ Γα, β (x))x∈X .
Hypergraph theory can lead to numerous other applications [HK00, HOS12, Rob39,
STV04, Smo07, Zyk74]. Indeed we can find hypergraph models in machine learning,
data mining, and so on [BP09, STV04, Sla78, Smo07, Rob39].
The properties of hypergraphs are equally important, for example hypergraph
transversal computation has a large number of applications in many areas of com-
puter science, such as distribued systems, databases, artificial intelligence, and so
on. Hypergraph partitioning is also a very interesting property [BP09, HK00]. The
partitioning of a hypergraph can be defined as follows:
(a) The set of vertices is partioned into k disjoint subsets V1 , V2 , . . . , Vk .
(b) The partial subhypergraphs (or the set of hyperedges) generated by V1 , V2 , . . . , Vk
verify the properties P1 , P2 , . . . , Pk .
This property yields interesting results in many areas such as VLSI design, data
mining, and so on.
Directed hypergraphs can be very useful in many areas of sciences. Indeed directed
hypergraphs are used as models in:
• Formal languages.
• Relational data bases.
• Scheduling.
and many other applications. Numerous computational studies using hypergraphs
have shown the importance of this field in many areas of science [Gol11, BP09,
116 7 Applications of Hypergraph Theory: A Brief Overview
Bre04, HOS12, Hua08] , and other fruitful applications should be developed in the
future.
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References