Sheila A. Greibach

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The notion of an abstract family of languages (AFL) as a family of sets of words satisfying certain properties common to many types of formal languages is introduced. Operations preserving AFL are then considered. The concept of an abstract family of acceptors (AFA) is also intro­ duced and shown to give rise to an AFL. A necessary and sufficient condition(More)
The quasi-realtime languages are seen to be the languages accepted by nondeterministic multitape Turing machines in real time. The family of quasi-realtime languages forms an abstract family of languages closed under intersection, linear erasing, and reversal. It is identical with the family of languages accepted by nondeterministic multitape Turing(More)
A deterministic pushdown store automaton ~s superdetermm~suc if it is finite delay, and whenever two accessible configurations c~ and c~ in the same state and m reading mode are taken by the same input into two configurations c, and c', m reading mode, then c, and c'_, are also m the same state and the change m stack height between c, and c_, is the same as(More)