1 CFGSConsider the following grammar.erpr := erpr + expr | erpr + erpr|(crpr) | numbernumber := number digit | digitdigit := 0 I 1 | 21 3I 4I5I 6I7 | 8 I 91. Redefine the grammar in a way that numbers are defined by regular expressions. That is, remove twogrammar rules for number and digit nonterminals, and replace them with a single regular expres-sions for numbers.2. Modify the grammar to define assignment statements with a syntax similar to C/C+, where ex-pressions are assigned to identifiers. Here are the steps:(a) Add identifier token ID to the CFG. You may define it with regular expressions (since identi-fiers are tokens). We have already seen how to define identifiers with regular expressions, inprevious sessions.(b) Consider a nonterminal for assignment. Let's call this nonterminal assignment. You need todefine a CFG rule that defines assignment. An assignment in C/C+ grammatically consists ofan identifier (defined in previous step), folowed by equality symbol (a terminal), followed byan expression (an already defined nonterminal). This sequence of terminals and nonterminalsshould be given in the RHS of your CFG rule.

Answered: 1 CFGS Consider the following grammar.…

Computer Networking: A Top-Down Approach (7th Edition)

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Author:James Kurose, Keith Ross

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Chapter1: Computer Networks And The Internet

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Question

1 CFGS
Consider the following grammar.
erpr := erpr + expr | erpr + erpr|(crpr) | number
number := number digit | digit
digit := 0 I 1 | 21 3I 4I5I 6I7 | 8 I 9
1. Redefine the grammar in a way that numbers are defined by regular expressions. That is, remove two
grammar rules for number and digit nonterminals, and replace them with a single regular expres-
sions for numbers.
2. Modify the grammar to define assignment statements with a syntax similar to C/C+, where ex-
pressions are assigned to identifiers. Here are the steps:
(a) Add identifier token ID to the CFG. You may define it with regular expressions (since identi-
fiers are tokens). We have already seen how to define identifiers with regular expressions, in
previous sessions.
(b) Consider a nonterminal for assignment. Let's call this nonterminal assignment. You need to
define a CFG rule that defines assignment. An assignment in C/C+ grammatically consists of
an identifier (defined in previous step), folowed by equality symbol (a terminal), followed by
an expression (an already defined nonterminal). This sequence of terminals and nonterminals
should be given in the RHS of your CFG rule.

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When working with text, whether authoring or editing, we often need to change something. Name of some feature from A to B. Spelling error. Numerical value. A phrase that does not fit the rest of text. And usually, we just delete the wrong text and type in the correct one. If a spelling error or incorrect spelling variant is repeated across the document, we may use Find/Change to correct all instances at once.