{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lec13Parse - Notetakers Justin Miller and Kenrick Goldson...

This preview shows pages 1–3. Sign up to view the full content.

Notetakers: Justin Miller and Kenrick Goldson COT 4210 Discrete Structures II 4 common searches: Breadth-First Top-Down Depth-First Top-Down Breadth-First Bottup-Up Depth-First Bottom-Up Algorithm: beginning at beginning of queue, explore all nodes of depth 1, then 2, 3, etc. Example I – Breadth-First Search( Top-Down ): Using the following, we derive a breadth-first top-down search for the expression (b+b). V = {S, A, T} ∑ = {b, +, (, )} 1. S A 2. A T 3. A A + T 4. T b 5. T (A) ( b ) / b ( T ) --- ( ( A ) ) / / T --- ( A ) --- ( A + T ) / S --- A b + T \ / A + T --- T + T --- ( A ) + T \ A + T + T --- T + T + T \ A + T + T + T NOTE: If string bb+ is searched for using Breadth-First Search Top-Down parsing method, it is possible for the search to continue forever since it is not part of the language.

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

View Full Document
Example II – Depth-First Search( Top-Down ): Using the same example, we search depth-first top-down for the expression (b+b). S / T / \ b (A) / \ (T) (A+T) / \ \ (b) ((A)) (T+T) / ( b + T ) / ( b + b ) Working backwards (bottom-up), we show that ( b + b ) is in the grammar S. ( b + b ) ( T + b ) ( A + b ) ( A + T ) ( A ) T A S An issue with this parsing method is that if one of the nodes goes on forever, then you will never get to the rest of the tree A stack keeps track of
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern