(definition)

**Definition:**
The class of *languages* for which membership can be determined in *polynomial time* by a *probabilistic Turing machine* with no false acceptances and less than half false rejections. "RP" means "**R**andomized **P**olynomial" time.

**Formal Definition:** For a language, S, there exists a *probabilistic Turing machine*, M, that *accepts* or rejects any string in *polynomial time*. If w ∉ S, M rejects w. If w ∈ S, M accepts w with a probability at least 1/2.

**Also known as** randomized polynomial time.

**See also**
*NP*, *ZPP*, *BPP*, *Monte Carlo algorithm*.

*Note:
By repeating the run, the chance of incorrect rejection may be arbitrarily reduced. *

* After [Hirv01, page 19].*

Author: PEB

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Entry modified 17 December 2004.

HTML page formatted Mon Feb 2 13:10:40 2015.

Cite this as:

Paul E. Black, "RP", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 17 December 2004. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/rp.html