Deep Pushdown Automata of Finite Index

This thesis introduces several modifications of deep pushdown automata considering the reduced number of states or non-input symbols. It is shown that the power of deep pushdown automata of finite index is not affected by a limitation of non-input symbols to one, thus these automata characterize an infinite hierarchy of language families resulting from programmed grammars of finite index. Based on a principle of these automata, it is established the normal form of deep pushdown automata. Finally, I introduce generalized deep pushdown automata. They expand the topmost possible non-input symbol in the pushdown. These automata and their reduced forms are equivalent to state grammars