CS622

Context-Free Languages (CFLs)

Announcements

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⇒ M w N w

• M w

• N w

⇐ N w M w

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→

L

L’sEXPANDc(L)

EXPANDc(L)

EXPANDc

Last Time:

https://docs.oracle.com/javase/specs/jls/se7/html/jls-2.html

https://docs.python.org/3/reference/grammar.html

https://docs.python.org/3/reference/grammar.html

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Flashback:

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ε

⇒

⇐

⇒

⇐

L

•

• ⇒ ⇐

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• EXPR ⇒

• EXPR TERM ⇒

• TERM TERM ⇒

• FACTOR TERM ⇒

• TERM

• EXPR ⇒

• EXPR TERM ⇒

• EXPR TERM ⨯ FACTOR ⇒

• EXPR TERM ⨯ ⇒

⨯

• EXPR =>

• EXPR + TERM =>

• TERM + TERM =>

• FACTOR + TERM =>

• a + TERM

• EXPR =>

• EXPR + TERM =>

• EXPR + TERM FACTOR =>

• EXPR + TERM a=>

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•• ELEMENT <TAG>CONTENT</TAG>

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• S -> 0C’0 | 1C’1 | ε

• C’ -> C’C | ε

• C -> 0 | 1

Check-in Quiz 9/29