ben@uunet.UU.NET (Ben Lian) (06/19/89)
To Tim Budd (@ Oregon?)
Sorry, erased your email address after responding re PARLE and
the Watson & Watson paper on weighted reference counting.
Further to my email, I thought you'd like to know that the Watson &
Watson algorithm was PATENTED (yes, patented) by ICL in the early
'80s. According to one of my colleagues, the patent covers all uses
of the algorithm in which the reference weight is split (in some
arbitrary ratio). This suggests that the patent covers most ANY
application of the algorithm. Bevan's algorithm, also in the PARLE 87
proceedings, is an elegant subset of Watson & Watson's. (Ironically,
Bevan won the 'best paper' award at the conference!) The patent permits
the use of the algorithm in research contexts only; use in a commercial
product is not allowed. (Which means that our Department's VLSI
parallel combinator reduction machine will never see the light of day.)
Ben Lian
P.S. On hearing that the algorithm had been patented, my colleague
ran up and down the corridor of our hut, exclaiming: "How could they
do this? They might as well patent the addition operator!"
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