Parallel Composition
A pipeline topology where a source fans out to N independent branches that later merge. Two variants. Parallel-AND requires every branch to clear (joint yield is still the product, no improvement over serial - only latency drops). Parallel-OR accepts when any branch clears (yield approaches 1 fast, the redundant-verifier pattern).
Why It Exists
Parallel-AND is what most people mean by "parallelize the pipeline" - and it does not improve correctness, only throughput. Parallel-OR is the underused redundancy pattern: when false-rejects are cheap, running two verifiers in parallel and accepting on either catches misses.
Related Terms
Serial Composition - A pipeline topology where each node feeds the next.
Verifier-Producer - A two-node topology where a producer P emits a candidate and a verifier V either accepts it (forwards to output) or rejects it (loops back to P for a rerun).