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From: gah4 <gah4@u.washington.edu>
Newsgroups: comp.compilers
Subject: Re: How detect grammar not derive nonterminals ?
Date: Tue, 12 Sep 2023 22:08:52 -0700
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On Tuesday, September 12, 2023 at 10:42:28 AM UTC-7, Andy wrote:

(the subject not included in the message)

> How detect grammar not derive nonterminals ?

Ethernet uses the spanning tree protocol to detect loops in a switched network.

I think the same idea works here, but didn't try it.