Lab for Automated Reasoning and Analysis LARA

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notes_on_context-free_grammars [2007/03/17 20:25]
vkuncak
notes_on_context-free_grammars [2007/03/18 17:11] (current)
vkuncak
Line 15: Line 15:
   N ::= w1 | w2   N ::= w1 | w2
   M ::= w3 | w4 | w5   M ::= w3 | w4 | w5
 +
 +Note that, when we write, for example,
 +
 +  N ::= a | N + N
 +
 +the two occurrences of N in "N + N" need not denote the same expression, they merely denote two subexpressions both of which conform to the syntax defined by N.  Sometimes, to make this clear and to make it possible to refer to individual occurrences,​ we can write subscripts, as in
 +
 +  N ::= a | N_1 + N_2
 +
 +using the convention that N_i denotes the same set of strings as N.
  
 
notes_on_context-free_grammars.txt · Last modified: 2007/03/18 17:11 by vkuncak
 
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