parallelism

par·al·lel·ism   (pār'ə-lě-lĭz'əm)    n.   The quality or condition of being parallel; a parallel relationship. Likeness, correspondence, or similarity in aspect, course, or tendency. Grammar The use of identical or equivalent syntactic constructions in corresponding clauses or phrases. Philosophy The doctrine that to every mental change there corresponds a concomitant but causally unconnected physical alteration.

Main Entry: par·al·lel·ism
Pronunciation: 'par-&-"lel-"iz-&m, -l&l-
Function: noun
: a philosophical or psychologicaldoctrine that there is a one-to-one correspondence between events in the mind and events in the brain but that the two sets of events exist without interacting in a causal way called alsopsychophysical parallelism

parallelism
1. parallel processing.
2. The maximum number of independent subtasks in a given task at a given point in its execution. E.g. in computing the expression
(a + b) *
(c + d) the expressions a, b, c and d can all be calculated in parallel giving a degree of parallelism of (at least) four. Once they have been evaluated then the expressions a + b and c + d can be calculated as two independent parallel processes.
The Bernstein condition states that processes P and Q can be executed in parallel (or in either sequential order) only if:
(i) there is no overlap between the inputs of P and the outputs of Q and vice versa and
(ii) there is no overlap between the outputs of P, the outputs of Q and the inputs of any other task.
If process P outputs value v which process Q reads then P must be executed before Q. If both processes write to some variable then its final value will depend on their execution order so they cannot be executed in parallel if any other process depends on that variable's value.
(1995-05-07)