Given the following grammar: -> | -> -> | -> | -> a| b | c -> 1 | 2 | 3 Indicate

Question

Given the following grammar: -> | -> -> | -> | -> a| b | c -> 1 | 2 | 3 Indicate which of the following strings are valid according to this grammar. For those that are valid, construct the parse tree. a1b2c3 (valid) abc123(valid) 12ab 11aa22 ab12c3(valid) In English, describe the strings generated by this grammar as specifically as possible. I already have the valid strings and the trees for each one of them. I just need help describing them in English. Thanks for your help.

Explanation / Answer

Its quite simple .. See, taking -> | as the start symbol , if we look carefully, whatever string we generate from the grammar it will always have an alphabet from a|b|c at its left owing to the grammar rules : -> -> | -> a| b | c and the numerical symbols at the right owing to the grammar rules :: -> -> | -> 1 | 2 | 3 Thus whatever String starts with an alphabet and ends with an numerical symbol is Valid and hence 1 , 2 and 5 are valid Hope it helps ... Since I'm posting the answer first .. plz rate me first so that I can get the Karma points .. thanks :)

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