Optimality Theory (frequently abbreviated
OT; second word normally capitalized by convention) is a
linguistic model proposing that the observed forms of
language arise from the interaction between conflicting constraints. OT differs from other approaches to phonological analysis, such as
autosegmental phonology and linear phonology (SPE), which typically use rules rather than constraints. OT models grammars as systems that provide mappings from inputs to outputs; typically, the inputs are conceived of as
underlying representations, and the outputs as their surface realizations.