On Sat, 16 Jun 2007 09:43:00 -0500, Tom Ring
wrote:

Any open source version(s) you would recommend? I may have to have a
look again.

Hi Tom,

I would like to say Trilogy, which is also a declarative language, but
long gone by nearly 20 years.

On the active front, there is XPCE/Prolog (google this) out of
Amsterdam. It appears to be the product of a one-man show and to my
mind suffers from what he thinks the language should be (and not what
it was). I suppose my attitude would be better if I could have read
the users manual which, unfortunately, mimics all the poorly written
user manuals that have come down the pike since PL/M.

73's
Richard Clark, KB7QHC