Empty String

An Empty String is a string with Zero Members.

• AKA: Null String, ε, λ.
• Context:
  • It can be detected by an Empty String Relation.
  • …
• Example(s):
  • "".
  • ...
• Counter-Example(s):
  • a Non-Empty String.
  • an Empty Set.
  • a Null Vector.
  • an Empty Graph.
• See:----

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References

2009

• (Wikipedia, 2009) ⇒ http://en.wikipedia.org/wiki/Empty_string
  • In computer science and formal language theory, the empty string is the unique string of length zero. It is denoted with "λ" or sometimes ϵ.
  • The empty string is distinct from a null reference in that in an object-oriented programming language a null reference to a string type doesn't point to a string object and will cause an error were one to try to perform any operation on it. The empty string is still a string upon which string operations may be attempted.

2007

• (Kakkonen, 2007) ⇒ Tuomo Kakkonen. (2007). “Framework and Resources for Natural Language Evaluation." Academic Dissertation. University of Joensuu.
  • Let [math]\displaystyle{ \Sigma }[/math] be an alphabet.
  • A finite sequence of symbols [math]\displaystyle{ S=(x_1 x_2 … x_n), n≥0, x \in \Sigma }[/math] is called a string in alphabet [math]\displaystyle{ \Sigma }[/math].
  • The length |S| of string S is n.
  • The empty string is the sequence of length 0; written [math]\displaystyle{ \varepsilon }[/math].

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