Thank you. The thing is that when talking about the semantic of Prolog,
one can choose any set as the semantic domain to start, and then a reason
is given for choosing the Herbrand universe.
On Sun, 30 Dec 2007 19:23:00 +0200, Benja Fallenstein
<[EMAIL PROTECTED]> wrote:
Hi Cristian,
On Dec 30, 2007 6:10 PM, Cristian Baboi <[EMAIL PROTECTED]> wrote:
What I don't get it :
(s a1 a2 ... at) must be the value of A in the semantic domain. Let call
that value a.
Then how can one know if a was built with (s a1 a2 ... at) and not with
(egg b1 b2) ?
Because the semantic domain is chosen so that (s a1 a2 ... at) and
(egg b1 b2) are distinct objects.
More precisely, the domain corresponding to (for example) the type
data T = C1 T11 T12 | C2 T21 T22
should be isomorphic to the domain
[[T]] = lift (([[T11]] * [[T12]]) + ([[T21]] * [[T22]]))
where * is cartesian product, + is disjoint sum (e.g., X+Y = {(1,x) |
x in X} union {(2,y) | y in Y}, and 'lift' adds the bottom element to
the domain.
So here, C1 and C2 correspond to the two sides of the disjoint sum,
meaning you can tell them apart.
Hope that helps?
- Benja
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