In computer science, an online algorithm is one that can process its input piece-by-piece in a serial fashion, i.e. , in the order that the input is fed to the algorithm, without having the entire input available from the start. In contrast, an offline algorithm is given the whole problem data from the beginning and is required to output an answer which solves the problem at hand.
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Competitive analysis (online algorithm)
Competitive analysis is a method invented for analyzing online algorithms, in which the performance of an online algorithm (which must satisfy an unpredictable sequence of requests, completing each request without being able to see the future) is compared to the performance of an optimal offline algorithm that can view the sequence of requests in advance. An algorithm is competitive if its competitive ratio¿the ratio between its performance and the offline algorithm's performance¿is bounded.
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P (complexity)
In computational complexity theory, P, also known as PTIME or DTIME(n), is one of the most fundamental complexity classes. It contains all decision problems which can be solved by a deterministic Turing machine using a polynomial amount of computation time, or polynomial time.
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Clairvoyance
The term clairvoyance (from French clair meaning "clear" and voyance meaning "vision") is used to refer to the ability to gain information about an object, person, location or physical event through means other than the known human senses, a form of extra-sensory perception. A person said to have the ability of clairvoyance is referred to as a clairvoyant ("one who sees clearly"). Claims for the existence of paranormal and psychic abilities such as clairvoyance are highly controversial.
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