[CCing groff list as it's also on-topic there, as troff history is to
both lists]

At 2025-05-25T10:59:13-0700, Adam Thornton wrote:
> I don't think I'd place that kind of faith in the LLM summary without
> having a good read first.
[...]

At 2025-05-25T16:13:58-0400, Norman Wilson wrote:
[...]
> LLMs are not search engines.  They are bullshit generators.

I had a similarly bad experience with troff history and the AI-generated
"answer" Google situated in prime visual real estate.

This "AI Overview" claimed:

"In troff, Brian Kernighan modified the text formatter to include a
sentence space, which adds extra space between sentences.  Specifically,
if the sentence space is not set to zero, the second space after a
potential end-of-sentence character (like ".", "?", or "!") will be
treated as a sentence space, adding extra vertical spacing."

My aggrieved rant, which some of my social media friends endured:

"Jeeeesus Christ.  I needed to look up some advice Kernighan wrote to
troff users decades ago and I got a gout of lies sprayed directly into
my face in an area where I might be able to call myself a domain expert.

Be VERY VERY careful accepting any AI-generated results, people.  This
shit is ALMOST COMPLETELY WRONG.  (It's correct about which punctuation
marks [can] end a sentence...but you already knew that part, didn't
you?)

1.  Kernighan didn't innovate this.  Ossanna troff (and nroff) already
implemented end-of-sentence inference.

2.  Configuration of inter-sentence spacing is a GNU troff extension,
something else Kernighan had nothing to do with.  Ossanna and Kernighan
troffs permitted configuration of the inter-WORD space size with the
`ss` request, but not the inter-SENTENCE space size.

3.  Inter-sentence space is NOT VERTICAL.  It's horizontal."