Re: Problem with a derivation tree
- From: William Elliot <marsh@xxxxxxxxxxxxxxxxxx>
- Date: Sun, 22 Oct 2006 07:14:01 -0700
On Sun, 22 Oct 2006, David C. Ullrich wrote:
<marsh@xxxxxxxxxxxxxxxxxx> wrote:On the hopes that someone would explain the question
On Sat, 21 Oct 2006 anandr86@xxxxxxxxx wrote:
In the book "Principles of compiler design, Aho Ullman" theInputs?! Don't get it.
following exercise caught my attention. The grammar given is
S -> aSa | aa
It is quoted that a "top down parse with backtracking" can establish
the inputs with 2,4 or 8 a's but not 6 a's .... How is this possible ?
Then why don't you let someone who understands the question try
replying?
or consider if 'inputs' was miscue for 'outputs'.
S -> aSa -> aaSaa -> aaaaaa is an output.
The grammar he's fantasizing is
S -> SS | aa
Shucks, S -> SS -> SSaa -> aaaaaa
.
- References:
- Problem with a derivation tree
- From: anandr86
- Re: Problem with a derivation tree
- From: William Elliot
- Re: Problem with a derivation tree
- From: David C . Ullrich
- Problem with a derivation tree
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