Information Retrieval System Explained: Types, Comparison & Components

An information retrieval (IR) system is a set of algorithms that facilitate the relevance of displayed documents to searched queries. In simple words, it works to sort and rank documents based on the queries of a user. There is uniformity with respect to the query and text in the document to enable document accessibility.

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This also allows a matching function to be used effectively to rank a document formally using their Retrieval Status Value (RSV). The document contents are represented by a collection of descriptors, known as terms, that belong to a vocabulary V. An IR system also extracts feedback on the usability of the displayed results by tracking the user’s behaviour.

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When we speak of search engines, we mean the likes of Google, Yahoo, and Bing among the general search engines. Other search engines include DBLP and Google Scholar. 

In this article, we will look at the different types of IR models, the components involved, and the techniques used in Information Retrieval to understand the mechanism behind search engines displaying results. 

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Types of Information Retrieval Model

There are several information retrieval techniques and types that can help you with the process. An information retrieval comprises of the following four key elements:

1. D − Document Representation.
2. Q − Query Representation.
3. F − A framework to match and establish a relationship between D and Q.
4. R (q, di) − A ranking function that determines the similarity between the query and the document to display relevant information.

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There are three types of Information Retrieval (IR) models:

1. Classical IR Model — It is designed upon basic mathematical concepts and is the most widely-used of IR models. Classic Information Retrieval models can be implemented with ease. Its examples include Vector-space, Boolean and Probabilistic IR models. In this system, the retrieval of information depends on documents containing the defined set of queries. There is no ranking or grading of any kind. The different classical IR models take Document Representation, Query representation, and Retrieval/Matching function into account in their modelling. This is one of the most used Information retrieval models.

2. Non-Classical IR Model — They differ from classic models in that they are built upon propositional logic. Examples of non-classical IR models include Information Logic, Situation Theory, and Interaction models. It is one of the types of information retrieval systems that is diametrically opposite to the conventional IR model. 

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3. Alternative IR Model — These take principles of classical IR model and enhance upon to create more functional models like the Cluster model, Alternative Set-Theoretic Models Fuzzy Set model, Latent Semantic Indexing (LSI) model, Alternative Algebraic Models Generalized Vector Space Model, etc.

Let’s understand the most-adopted similarity-based classical IR models in further detail: 

1. Boolean Model — This model required information to be translated into a Boolean expression and Boolean queries. The latter is used to determine the information needed to be able to provide the right match when the Boolean expression is found to be true. It uses Boolean operations AND, OR, NOT to create a combination of multiple terms based on what the user asks. This is one of the information retrieval models that is widely used. 

2. Vector Space Model — This model takes documents and queries denoted as vectors and retrieves documents depending on how similar they are. This can result in two types of vectors which are then used to rank search results either 

• Binary in Boolean VSM.
• Weighted in Non-binary VSM.

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3. Probability Distribution Model — In this model, the documents are considered as distributions of terms and queries are matched based on the similarity of these representations. This is made possible using entropy or by computing the probable utility of the document. They are if two types:

• Similarity-based Probability Distribution Model
• Expected-utility-based Probability Distribution Model

4. Probabilistic Models — The probabilistic model is rather simple and takes the probability ranking to display results. To put it simply, documents are ranked based on the probability of their relevance to a searched query. This is one of the most basic information retrieval techniques used. 

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Components of Information Retrieval Model

Here are the prerequisites for an IR model: 

1. An automated or manually-operated indexing system used to index and search techniques and procedures.
2. A collection of documents in any one of the following formats: text, image or multimedia.
3. A set of queries that serve as the input to a system, via a human or machine.
4. An evaluation metric to measure or evaluate a system’s effectiveness (for instance, precision and recall). For instance, to ensure how useful the information displayed to the user is. 

If you draw and explain the IR system block diagram, you will come across different components. The various components of an Information Retrieval Model include: 

Step 1

Step 2

Step 3

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Step 4

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Importance of Information Retrieval System

What is information retrieval? Information is a vital resource for corporate operations, and it has to be managed effectively, just like any other vital resource. However, rapidly advancing technology is altering how even very tiny organizations manage crucial business data via information retrieval in AI. A business is held together by an information or records management system, which is most frequently electronic and created to acquire, analyze, retain, and retrieve information.

After we understand what is information retrieval, we need to understand its importance. 

Here are some reasons why Information Retrieval in AI is important in today’s world – 

• Productive and Efficient – It is unproductive and possibly expensive for small businesses and local companies to have an owner or employee spend time looking through piles of loose papers or attempting to find records that are missing or have been improperly filed. In addition to lowering the likelihood of information being misfiled, robust information storage and retrieval system that includes a strong indexing system also accelerates the storing and information extraction. This time-saving advantage results in increased office productivity and efficiency while lowering anxiety and stress.
• Regulatory Compliance – A privately owned corporation is exempt from the majority of federal and state compliance regulations, unlike a public company. Despite this, many people decide to voluntarily comply in order to increase accountability and the company’s reputation in public. Additionally, small-business owners are required to retain and maintain tax information so that it is easily available in the event of an audit. A well-organized system for information retrieval in Artificial Intelligence that adheres to compliance rules and tax record-keeping requirements greatly boosts a business owner’s confidence that the operation is entirely legal.
• Manual vs. Electronic – The value of electronic information retrieval in Artificial Intelligence is based on the fact that they demand less storage space and cost less in terms of both equipment and manpower. An ordered file system may be maintained using a manual approach, but it requires financial allotments for storage space, filing equipment, and administrative costs. Additionally, an electronic system may make it much simpler to implement and maintain internal controls intended to prevent fraud, as well as make sure the company is adhering to privacy regulations.
• Better Working Environment – Anyone passing through an office space may find it depressing to see important records and other material piled on top of file cabinets or in boxes close to desks. Not only does this lead to a tense and unsatisfactory work atmosphere, but if consumers witness this, it could give them a bad impression of the company. To understand how crucial it is for even a small firm to have efficient information storage and retrieval system.

Difference Between Information Retrieval and Data Retrieval

Data Retrieval systems directly retrieve data from database management systems like ODBMS by identifying keywords in the queries provided by users and matching them with the documents in the database. 

Whereas the Information Retrieval system in DBMS is a set of algorithms or programs that involve storing, retrieving, evaluation of document and query representations, esp text-based, to display results based on similarity.

User Interaction with Information Retrieval System

Now that you understand “what is information retrieval system,” let us understand the concept of user interaction with it. 

The User Task

It begins with the rise of a query from the information converted by the user. In an information retrieval system, conveying the semantics of the requested information is possible through a collection of words.

Logical View of the Documents

In the past, index terms or keywords were used for characterizing documents. Now, new computers can portray documents with a whole set of words. It can minimize the number of representative words. It is possible by deleting stop words like connectives and articles. 

Understanding the Difference Between IRS and DBMS

Let us discover the difference between IRS and DBMS here.

Exploring the Past, Present, and Future of Information Retrieval

After becoming aware of the information retrieval system definition, you should explore its past, present, and future:

• Early Developments: With the increasing need for gaining information, it also became necessary to build data structures for faster access. The index acts as a data structure for supporting fast information retrieval. For a long time, indexes involved manual categorization of hierarchies. 
• Information Retrieval in Libraries: The adoption of the IR system for information was popularized by libraries. In the first generation, it includes the automation of previous technologies. Therefore, the search was done according to the author’s name and title. In the second generation, searching is possible using the subject heading, keywords, and more. In the third generation, the search is possible using graphical interfaces, hypertext features, electronic forms, and more. 
• The Web and Digital Libraries: After learning the definition of an information retrieval system, you will realize that it is less expensive than various other sources of information. Therefore, it offers greater access to networks through digital communication. Moreover, it provides free access to publishing on a larger medium. 

Conclusion

This brings us to the end of the article. We hope you found the information helpful. If you are looking for more knowledge on Data Science concepts, you should check out India’s 1st NASSCOM certified Executive PG Program in Data Science from IITB on upGrad. 

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