{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

automata-7 - Automata Chapter 7 Pushdown Automata Chpater 7...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Automata Chapter 7. Pushdown Automata
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Chpater 7 Pushdown Automata Automata for context-free languages? - can count without limit. i.e., L={a n b n | n 0} - Store and match a sequence of symbols in reverse order. i.e. L={ww R | w ∈∑ *} Stack as an unbounded storage. Pushdown automata(PDA). Control unit input Stack
Background image of page 2
7.1 Nondeterministic PDA Definition 7.1 A nondeterministic pushdown accepter (NPDA) is M=(Q, , Γ , δ , q 0 , z, F), where Q: a finite set of internal states of the control unit, : input alphabet, Γ : a finite set of symbols, stack alphabet, δ : Q x ( { λ }) x Γ finite subset of Q x Γ *, q 0 : initial state of the control unit z: stack start symbol, F Q : set of final states Control unit input Stack
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
7.1 Nondeterministic PDA Ex 7.1 a transition rules of an NPDA δ (q 1 , a, b) = {(q 2 , cd), (q 3 , λ )}. Ex 7.2 L= {a n b n : n 0} {a} Q ={q 0 , q 1 , q 2 , q 3 }, = {a, b}, Γ ={0, 1}, z=0, F={q 3 }, δ (q 0 , a, 0)={(q 1 , 10), (q 3 , λ )}, δ (q 0 , λ , 0)={(q 3 , λ )}, δ (q 1 , a , 1)={(q 1 , 11 )}, δ (q 1 , b , 1)={(q 2 , λ )}, δ (q 2 , b , 1)={(q 2 , λ )}, δ (q 2 , λ ,0)={(q 3 , λ )}.
Background image of page 4
7.1 Nondeterministic PDA Triplet (q, w, u) : instantaneous description of a PDA where q: state, w: unread part of the input string, u: stack contents A move by (q 1 , aw, bx) (q 2 , w, yx) iff (q 2 , y) δ (q 1 , a, b). Control unit input Stack
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
7.1 Nondeterministic PDA Definition 7.2 Let M=(Q, , Γ , δ , q 0 , z, F) be a NPDA.
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}