Pushdown Automaton: CFL and the pumping lemma

Example: L = {a i b i c j d j |i,j0}
Construct a PDA to recognize:
L = {a i b i c j d j |i,j0}
We will use the empty stack model.
The basic idea:
• Push to the stack an A for each a, pop an A
for each b.
• Push to the stack a C for each c, pop a C for
each d .
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