Algorithm for calculating relevance of documents in information retrieval systems

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 243
Algorithm for calculating relevance of documents in
information retrieval systems
Roberto Passailaigue Baquerizo1, Paúl Rodríguez Leyva2, Juan Pedro Febles3, Hubert Viltres
Sala4, Vivian Estrada Sentí5
1Canciller Universidad Tecnológica (ECOTEC)
Guayaquil, Ecuador
2Departamento de Soluciones Informáticas para Internet,
Universidad de las Ciencias Informáticas,
La Habana, Cuba
3Departamento Metodológico de Postgrado,
La Habana, Cuba
4Departamento de Preparación Profesional
La Habana, Cuba
3Departamento Metodológico de Postgrado,
La Habana, Cuba
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Abstract - This research belongs to the field of information
retrieval and its main objective is the basis of an algorithm to
assign the value of relevance to a document concerning a
consultation inserted by users on information retrieval
systems. The concept of relevance is a fundamental aspect in
the design and development of information retrieval systems,
because although these tools performathoroughsearchof the
web, a correct structuring of documents and an efficient
storage of the same, if the user it does not obtain the results
that actually respond to its search needs, then the quality of
the information retrieval system is penalized by the
acceptance criteria of the users. The algorithm is based
primarily on the classical mathematical expressions for
calculating similarity between groups, known as the cosine,
jaccard and dice formulas. It has the particularity variationof
the similarity based on the relationship established between
the search profile of users and categories of documents stored
in information retrieval system. In order to get thesevariables
are used text mining and web mining techniques allowing the
processing of the information generated by the registration of
user queries and metadata stored documents? The main
contribution of the research is an algorithm to calculate the
relevance of the documents that are provided as part of the
responses to queries made by users
Key Words: algorithm, similarity, queries, information
retrieval systems, relevance
1. INTRODUCTION
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look exactly like this document. The easiest way to do this is
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the authors name can be used along with the reference
number in the running text. The order of reference in the
running text should match with the list of references at the
end of the paper. Information Retrieval (IR) is not a new
area, but is being developed since the late fifties. However,it
now plays a more important role given the value of the
information. It can be argued that having or not having the
right information in a timely manner can lead to the success
or failure of an operation. Therefore, the importance of
information retrieval systems (SRI)canhandle -withcertain
limitations - these situations effectively and efficiently [1].
From 1950 to the present many concepts have addressed
this particular issue. According to Baeza Yates, one of the
most experienced researchers in this field, the term "deals
with representation, storage, organization and access to
information elements". This concept is defined by Salton as
"a field related to the structure, analysis, organization,
storage, search and retrieval of information" [11]. Croft
estimates that information retrieval is "the set of tasks by
which the user locates and accesses information resources
that are relevant to problem resolution." Documentary
languages, abstract techniques, description of the

documentary object, etc. These tasks. "[4]Ontheotherhand,
Korfhage defined IR as" the location and presentation to a
user of information relevant to a need for information
expressed as a question "[15].
From the concepts previously provided, it can be inferred
that IR is the process of locating andstoringinformationthat
is then accessed by users depending on the search needs of
the same. One of the ways most used by users to access the
entire cluster of information hosted on the web are search
engines. These tools have a set of components that allow the
crawling, indexing and visualization of the collected
information as part of the responses offered to the users
after they execute a query. They can also be defined as
software agents, programs that reside in a computer (host)
and have the mission of registering, classifying,indexingand
storing documents in the most diverse sites in automated
form. In addition, they present the possibility of accessing
these databases for consultation.Theyordertheinformation
[14].
A searcher employs different algorithms and methods to
satisfy the need for information raised by a user in a natural
language query specified through a set of keywords [6, 2].
Algorithms that provide relevant documentsina websearch
system need to perform an analysisofthesedocuments.This
process is based on the generation of an index of relevance
between documents for the terms included in them.
Generally the analysis performed to generate this index is
performed by the search engine but the retrieval of the
information is done by a web crawler or web spider [9]. In
an interview with Baeza Yates, this researcher explains the
following referring to the problematic of the IR, "the current
objective is to try to understand the intention after the
search. That is, what the person wants to do and personalize
their search for that task. "However, classic information
retrieval models do not handle variables such as usersearch
preferences; so it is necessary a way to integrate this
variable to the calculation of similarity that defines the
relevance of the documents in such models.
2. MATERIALS AND METHODS
Irjet Template sample paragraph .Define abbreviations
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after they have been defined in the abstract. Abbreviations
such as IEEE, SI, MKS, CGS, sc, dc, and rms do not have to be
defined. Do not use abbreviations in the title or heads unless
they are unavoidable.Searchenginesorinformationretrieval
systems have a number of components, each with a specific
function, as shown in Figure 1. Many of these tools base their
operation on theclassicmodelsofinformationretrieval.They
are recognized as: Boolean Model: The Boolean model is one
of the simplest informationretrievalmodelstouse.Itisbased
on Boolean set theory and algebra. In this model the queries
are logical expressions in which the operands are properties
of the documents. Pure Boolean operators are conjunction,
disjunction, and negation (AND, OR, NOT). In addition, most
systems include proximity operators and simple regular
expressions. In general, in these systems the user refines the
query until the number of relevant documents retrieved is
reasonable [7].
Fig – 1: Basic architecture of a search engine [15].
Probabilistic model [10]: This model is based on the fact
that in the IR process it is intrinsically imprecise. Within the
process itself, there are certain aspects that are non-
deterministic, forexample:Therepresentationthatmakesa
query of the need for information of the user.  The
representation of the documents in the system. With this in
mind, the probabilistic model postulates that the best way to
represent this is through probability theory. This model
attempts to estimate the probability that, given a query q, a
document d is relevant to that query. This is denoted as: P
(Rel | d). The model tries to obtain a set of relevant
documents (called R),whichshouldmaximizetheprobability
of relevance. A document is considered relevant if its
probability of being relevant, P (Rel | d), is greater than the
probability of not being relevant, P (noRel | d) [3]. Vector
model: Salton was the firsttoproposeSRI-basedvectorspace
structures in the late 1960s within the framework of the
SMART project. Since documents can be represented asterm
vectors, documents can be placed in a vector space of m
dimensions, with as many dimensions as components have
the vector [13]. The fundamental idea on which the vector
model is based is to consider that both the key terms with
respect to a document and the queries can be represented
through a vector in a space ofhigh dimensionality.Therefore,
to evaluate the similarity between a document and a query;
simply make acomparison of thevectorsthatrepresentthem
[12]. The three models have algorithms that allow ordering
documents taking into account the relevance in relation to a
query inserted by the user. Inthis modeltheusefulwordsare
selected, which are usually all the terms of the texts, except
the empty words; this processisenrichedusingtechniquesof
tagging and labeling. The similarity in the vector model
corresponds to the angle between thevectorofthedocument
and the vector of the query. If the angle betweenbothvectors
is 0 °, they are identical, whereas if the angle is 90°,theyhave

absolutely nothing in common. The main advantages of the
vector model are the following [10]:Allowpartialhits,since
a document can be considered relevant even if it does not
include all the terms of the query.  The ordering of results is
based on several factors: frequency of terms, importance of
terms and withoutprioritizinglongerdocuments.Inaddition,
it allows an efficient implementation for large collections of
documents. The documentsarelocatedindimensionalvector
spaces defined by the same terms. Thus ifeachtermdefinesa
dimension and the frequency of that term defines a linear
scale along that dimension, queries and documents can be
represented by vectors in the resulting space. Each term of
the queries and documents isweightedbyassigningthemthe
inverse value of the frequency of the term in the documents
of the collection (IDF - Inverse Document Frequency). This
value is calculated using the following equation [8]:
Equation 1. Calculating the idf
Where N is the number of documentsinthecollectionand
nt is the number of documents where the term t appears. The
weight of a term t in the document vector is given by the
equation: [8]
Equation 2. Calculation of the weight of a term
Where, f t, d is the absolute frequency of the term t, in the
current document.
The search algorithmacceptsas inputa query expression
or query of a user and will verify in the index which
documents can satisfy it. Then, a ranking algorithm will
determine the relevance of each document and return a list
with the answer. It is established that the firstitemofsaidlist
corresponds to the most relevant document regarding the
query and so on in decreasing order [15]. With the elements
for the retrieval of documents, wecan calculatethesimilarity
between a vector of weightsof the terms of the queryq,anda
vector of weights of the terms of document d, with the
following equations [8]:
Equation 3. Cosine
Equation 4. Jaccard
Equation 5. Dice
With the application of these equations we obtain a
similarity value between 0 and 1 that allows assigning a
relevance to a document with respect to a query.
3. RESULTS AND DISCUSSION
The algorithm proposed below allows to add to the
equations of similarity presented aboveavariable(SC)
that relates the user search preferences or search
profile (PBU) to the categories of stored documents
(CDoc). In order to obtainthePBUandthustoestablish
which category (s) are the most sought by the users
and also to obtain the categories of the documents
stored CDoc, the use of web mining techniques is
proposed. Figure 2. Web mining (MW) refers
essentially to the discoveryandanalysisofinformation
from users on the web, with the aim of discovering
patterns of behavior [16].
Fig - 2: Web mining process [5]

After defining each of the categories on which the
categorization process will be based, proceedtoassign
a numerical value to each one of them. Figure 3.
Fig -3: Allocation of numerical value to the categories
(Authors´ elaboration)
After the user search preferences are defined as a
result of the categorization of each of the previously
entered queries, these are sorted according to the
percentage of predominance (P) of the most consulted
categories. If there is only one predominant category,
the PBU would be equal to the numerical value of this
category.Ifmorethanonecategoryispredominantand
have the same value of P, the PBU would be a list with
the values of these categories Figure 4. With the PBU
defined and the documents categorized, we proceedto
compare the numerical values the predominant
categories with the category of each documents Figure
5.
Fig -4: Example of user profile (Authors´
elaboration)
Fig -5: PBU- CDoc comparison (Authors' elaboration)
If these values coincide, the variable SC acquires the
value of P, Figure 6, ensuring that the value of SC is
greater when the document belongs to the same group
of the category (s) defined in its PBU; otherwise the
value of SC is 0 meaning that the category of the
document is not related to the PBU, Figure 7.
Fig -6: Value assignment to SC (Authors´ elaboration)
Fig -7: Example of value of SC = 0 (Authors´
elaboration)
Once the value of SC is calculated,thisvariableisadded
to the result of the equation of similarity (Cosine,
Jaccard or Dice) used in the vector model applied, the
resulting valuewouldbetherelevanceofthedocument
with respect to the query entered by the user. The
threshold of similarity initially calculated ranges from
0 to 1, the most relevant documents being the closest
to 1. When the SC variable is added and its value added
to the initial similarity, the threshold of similarity

1’st
Author
Photo
increases from 0 to 2 Figure 8, the most relevant
documents are those close to 2. In this way it is
guaranteed to provide users with more accurate and
better results related to their search preferences.
Fig -8: Similarity threshold (Authors´ elaboration)
4. CONCLUSIONS
As fundamental conclusions of the investigation it
can be said that:
The vector IR model has mechanisms that allow a
structuring of documents and user queries that create
concrete bases for the process of calculatingrelevance.
The classic formulas for calculatingsimilaritydonotby
themselves satisfy the problem of assigning relevance
to documents in an SRI. The use of web mining to
process the information stored in an SRI allows
inferring important data such as the search profile of
users and the category of each indexed document. A
proposal of relevance calculation was obtained that
integrates variables such as the PBU and CDoc, which
allow users toprovideanswersthataremorerelatedto
their search needs.
REFERENCES
[1] Baeza-Yates, r. Y Ribeiro-Neto, b. (1999). Modern
Information Retrieval. ACM Press.Addison Wesley.
[2] Blázquez Ochando. (2013). Manual Técnicas avanzadas
de recuperación de información: procesos, técnicas y
métodos. Madrid. ISBN 978-84-695-8030-1.
[3] Cacheda, M. (2008). Introduction to the Classic Models of
Information Retrieval. Revista General de Información y
Documentación. (18):365-374.
[4] Croft, W.B. (1987). Approaches to intelligentinformation
retrieval. Information Proccesing & Management, 23, 4,
pp. 249-254.
[5] Fuentes Reyes, Sady C.; Ruiz Lobaina, Marina. (2007).
Minería Web: un recurso insoslayable para el
profesional de la información. Acimed, vol. 16,no4,p.0-
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[6] Jaimes, l. G y Vega Riveros. F. (2005). Modelos clásicos
de recuperación de la información.
[7] Machado García, Neili. (2015). Uso de la similitud
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[8] Monsalve, Luz Stella Garcia. (2012). Experimento de
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[9] Pino Toledano, David. (2014). Creación de un crawler
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[10] Reyna, Yunior César Fonseca. (2012). Recuperación de
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[11] Salton, G. Y MC Gill, m.j. (1983). Introduction to Modern
Information Retrieval. New York. Mc Graw-HillComputer
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indexación y recuperación de documentos utilizando
referencias geográficas y textuales.
[12] Sequera, José Luis Castillo. (2010). Nueva propuesta
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[13] Seroubian, Mabel. (2013). Buscadores: cómo usar las
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[14] Tolosa, Gabriel H.; Bordignon, Fernando R. (2008).
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[15] Vásquez, Augusto Cortez; Fernández,CayoLeón.(2016).
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no 3, p. 155-164.
BIOGRAPHIES
Ph.D Education,CancillerUniversity
ECOTEC, Ecuador
Ph.D Computing, Adviser
postgraduate, Habana, Cuba
Ph.D Computing, Adviser
postgraduate, Habana, Cuba
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