We classify the univariate functions that are relativizable
closure properties of GapP, solving a problem posed by Hertrampf,
Vollmer, and Wagner (Structures '95). We also give a simple proof of
their classification of univariate functions that are relativizable
closure properties of #P.

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We give new evidence that quantum computers -- moreover, rudimentary quantum computers built entirely out of linear-optical elements -- cannot be efficiently simulated by classical computers. In particular, we define a
model of computation in which identical photons are generated, sent through a linear-optical network, then nonadaptively measured to count ... more >>>