Wednesday 9 October 2013

ALGORITHM DEFINITION AND AN EXAMPLE OF A REAL WORLD APPLICATION

DEFINITION

        An  algorithm is defined as finite sequence  of unambiguous instructions followed to accomplish a given task. It is also defined as unambiguous, step by step procedure (instructions) to solve a given problem in finite number of steps by accepting a set of inputs and producing the desired output.

VARIOUS WAYS USED TO SPECIFY ALGORITHMS

An algorithm is usually specified in the following ways :
  • Natural language : Algorithms can be written in English like statements with very little mathematical expressions. The instructions specified in natural language must be clear and unambiguous. Normally, algorithms in natural language are not preferred due to its inherent ambiguity. So, it is rarely used.
  • Flowchart : A flowchart is a pictorial representation of an algorithm. That is, flowchart consists of sequence of instructions that are carried out in an algorithm. All the steps are drawn in the form of different shapes of boxes, circles and connecting arrows. These shapes represent various operations that are carried out.
  • Pseudo  code : The pseudo code is a method of representing an algorithm using natural language and programming language constructs. Thus, pseudo code is a mixture of natural language and programming constructs. The pseudo code may be similar in many respects to higher languages such as C, Pascal or Java.

AN REAL WORLD APPLICATION OF USAGE OF ALGORITHM : FACEBOOK GRAPH SEARCH

        Facebook Graph Search is a semantic search engine that was introduced by Facebook in March 2013. It is designed to give answers to user natural language queries rather than a list of links. The Graph Search feature combines the big data acquired from its over one billion users and external data into a search engine providing user-specific search results. In a presentation headed by Facebook CEO Mark Zuckerburg, it was announced that the Graph Search algorithm finds information from within a user's network of friends. 

http://upload.wikimedia.org/wikipedia/en/5/5d/Facebook_Graph_Search.jpg

Operation

        Graph Search operates by use of a search algorithm similar to traditional search engines such as Google. However, the search feature is distinguished as a semantic search engine, searching based on intended meaning. Rather than returning results based on matching keywords, the search engine is designed to match phrases, as well as objects on the site. The service processes searches of up to 112 characters.<not true: supports longer searches such as (for example): "People who live in Dublin, Ireland and who like Totally Enormous Extinct Dinosaurs and who like Rage Against The Machine"     >
        
        Search results are based on both the content of the user and their friends’ profiles and the relationships between the user and their friends. Results are based on the friends and interests expressed on Facebook, and also shaped by users’ privacy settings. In addition to being restricted from seeing some content, users may be able to view relevant content made publicly available by users that are not listed as friends.

        
      Entries into the search bar are auto-completed as users type, with Facebook suggesting friends and second degree connections, Facebook pages, automatically-generated topics, and finally Web searches for anything Facebook is not yet able to search for.


       The operation of the search feature depends on user involvement. The feature is intended to promote users to add more friends, more quickly. In doing so, it can provide updating, more data-rich results and stimulate use of the feature.

Search functions

Facebook supports searches for the following types of

  • Places (limitable to a specific location (latitude and longitude) and distance)
  • Check-ins of the user, friends, or where user or friends have been tagged
  • Objects with location information attached. In addition, the returned objects will be those in which the user or friends have been tagged, or those objects that were created by the user or friends.
Users can filter results, such as in time (since and until), or search only a given user's News feed.

 

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