Theory Of Computation Basics

Computation here is any task that can be calculated by a computer, calculator or any machine.
So to calculate and efficiently sought out the problem with the help of algorithms, thermos is computation and the study of it at start level is theory of computation.

We can say it as a core theory of computer science for algorithm and computer to solve problems.

Basic Terminology in TOC :

Symbols : They are the fundamental building block.

Example : 0,1, &, $, a, b, A ... so on.

Alphabets :  As we have 26 alphabets in English which make our English language. The same way the collection of symbols that constitute a computational language are called alphabets for the language.

For Example : Set of a,b symbols which is represented in curly brackets {a,b} is our alphabet

Strings : Sequence of symbols from a alphabets are called strings.

For Example : abab is a string of length of 4.

You can compare this hierarchy by English language where we have characters ( symbols), collection of characters (26 in English as alphabets here), sentence (as strings).

Point of concerned :

 If {a,b} is the alphabet then how many strings of length 2 are possible.

Solution : The string could be 

         ab, ba, aa, bb

 Means total 4 strings are possible.

Length of 3 possible?

aab, aba, abb, aaa, bab, bba,baa,  bbb

Means total 8 strings are possible.