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Similar notions include honest functions, [[space-constructible function]]s, and [[time-constructible function]]s.
Similar notions include honest functions, [[space-constructible function]]s, and [[time-constructible function]]s.

<ref>Alexei Myasnikov, Vladimir Shpilrain, Alexander Ushakov. Group-based Cryptography. Birkhäuser Verlag, 2008, p.28</ref>


==References==
==References==
{{Reflist}}
{{Reflist}}
{{cite book |last1=Myashnikov |first1=Alexei |last2=Shpilrain |first2=Vladimir |last3=Ushakov |first3=Vladimir |title=Group-based Cryptography |date=2008 |publisher=Birkhauser |isbn=978-3-7643-8826-3 |page=28}}


{{DEFAULTSORT:Proper Complexity Function}}
{{DEFAULTSORT:Proper Complexity Function}}

Latest revision as of 03:16, 6 April 2022

A proper complexity function is a function f mapping a natural number to a natural number such that:

  • f is nondecreasing;
  • there exists a k-string Turing machine M such that on any input of length n, M halts after O(n + f(n)) steps, uses O(f(n)) space, and outputs f(n) consecutive blanks.

If f and g are two proper complexity functions, then f + g, fg, and 2f are also proper complexity functions.

Similar notions include honest functions, space-constructible functions, and time-constructible functions.

References

[edit]

Myashnikov, Alexei; Shpilrain, Vladimir; Ushakov, Vladimir (2008). Group-based Cryptography. Birkhauser. p. 28. ISBN 978-3-7643-8826-3.