parallel processing, the concurrent or simultaneous execution of two or more parts of a single computer program, at speeds far exceeding those of a conventional computer. Parallel processing requires two or more interconnected processors, each of which executes a portion of the task; some supercomputer parallel-processing systems have hundreds of thousands of microprocessors. The processors access data through shared memory. The efficiency of parallel processing is dependent upon the development of programming languages that optimize the division of the tasks among the processors.

parallel of latitude: see latitude.

parallel circuit: see electric circuit.

Event in women's gymnastics in which a pair of wooden bars supported horizontally above the floor at different heights is used to perform acrobatic feats. The apparatus allows a great variety of movements, but hanging and swinging exercises predominate. It became an Olympic event in 1936. Seealso parallel bars.

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Evolution of geographically separated groups in such a way that they show physical resemblances. A notable example is the similarity between the marsupial mammals of Australia and placental mammals elsewhere, which have arrived at remarkably similar forms through the separate courses of their evolution.

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Event in men's gymnastics in which a pair of wooden bars supported horizontally above the floor at the same height is used to perform acrobatic feats. Competitors combine swings and vaults with stationary positions requiring strength and balance, though swings and vaults must predominate. It has been included as an Olympic gymnastics event since the modern games began in 1896. Seealso uneven parallel bars.

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