MHB Easy question regarding symbols in discrete mathematics

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The set of symbols that constitute strings in discrete mathematics is denoted by the symbol Σ, representing the alphabet. In contrast, Σ* denotes the set of all finite strings that can be formed from the symbols in Σ, including the empty string. The Kleene Star (*) indicates that the strings can consist of zero or more symbols. Therefore, Σ refers to the basic set of symbols, while Σ* encompasses all possible combinations of those symbols. Understanding this distinction is fundamental in the study of formal languages and automata theory.
shamieh
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is the set of symbols that make up strings denoted by the symbol Σ or Σ* , also what is this difference?
 
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Usually the set of symbols, or the alphabet, is denoted by $\Sigma$. Then $\Sigma^*$ denotes the set of all finite strings in the alphabet $\Sigma$.
 
The star (*) is the so called Kleene Star.
It means zero-or-more.

So indeed, Σ is the alphabet, while Σ* is the set of strings consisting of zero or more symbols from the alphabet.
 
First trick I learned this one a long time ago and have used it to entertain and amuse young kids. Ask your friend to write down a three-digit number without showing it to you. Then ask him or her to rearrange the digits to form a new three-digit number. After that, write whichever is the larger number above the other number, and then subtract the smaller from the larger, making sure that you don't see any of the numbers. Then ask the young "victim" to tell you any two of the digits of the...

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