Re: NFA to DFA

[jsa@organon.com (Jon S Anthony)]

In article <31987C20.167EB0E7@escmail.orl.mmc.com> "Theodore E. Dennison" <dennison@escmail.orl.mmc.com> writes:

> Being an old Modula-2 programmer (where Sets are basic structure types,
> like records), I have several times sat down to implement a generic
> SET ADT package. Every time, I have discovered that arrays of boolean
> give me exactly what I want with one simple type declaration. This
> is because Ada defines the boolean operators AND and OR to work on 
> ARRAYS of boolean in a bitwise fashion. So why bother with some fancy
> generic ADT package (that might have bugs)?

Simple.  If the universe over which you can construct sets is "big",
but the sets themselves are typically not "so big" relative to the
universe (the cardinality of the compliment of any set >> cardinality
of the set - at least typically...) then the array of boolean impl.
offers poor quality of service (maybe not even plausible...).  Also,
in Ada95, another reason is to allow a kind of dynamic QOS based on
universe size.  I suppose this latter wouldn't be so much "generic"
as "abstract".

Lest you think this is not very plausible to occur ("too big" universe),
just think of "wide characters".

/Jon

-- 
Jon Anthony
Organon Motives, Inc.
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Belmont, MA 02178

617.484.3383
jsa@organon.com