The exclusion of the *ABA pattern means that there should theoretically exist no language with a pattern analogous to *"good – better – goodest". AAB patterns (in which the superlative is suppletive but the comparative builds off the bare adjective) are theoretically possible as well but happen to be rare in the world's languages. Under the model of Distributed Morphology, the structure of a superlative would be [SPRL [CMPR [ADJ Adjective ] Comparative ] Superlative ]. Thus, the exponent of the comparative morpheme attaches to the bare adjective and the exponent of the superlative morpheme attaches to the comparative form (or replaces it in the suppletive cases). The following rules may be posited for Czech as an example: