On Sun, Dec 9, 2018 at 11:55 AM Ivan Vodišek <[email protected]> wrote: > > Oh, I see, I must be talking about URE then. All cool, then it seems > reasonable to me (one ring to rule them all - policy). > > I keep persuading myself that a perfect single declarative - logic + lambda > calculus + type theory exists, or could be invented,
So, OK, the atomspace is trying to be: + declarative: so kind-of-like datalog or kind-of like SQL or noSQL, or some quasi-generic (graph) data store. But you already know this. - it does NOT have "logic" in it, in any traditional sense of the word "logic". It does have the ability to perform term-rewriting (pattern re-writing, graph re-writing). - lambda calculus is a form of "string rewriting". Note that string rewriting is closely related to term rewriting (but not quite the same thing) and that term rewriting is closely related to graph rewriting (but not quite the same thing). When lambda calculus was invented, any distinction between strings, terms, and graphs was unknown and unknowable, until the basic concepts got worked out. So, due to "historical accident", generic lambda calculus remains a string rewriting system. As stuff got worked out over the 20th century, the concept of "term rewriting" gelled as a distinct concept. (And other mind-bendingly similar-but-slightly-different ideas, like universal algebra, model theory ... and bite my tongue. There's more that's "almost the same as lambda calc. but not quite". A veritable ocean of closely related ideas.) >From practical experience with atomspace, it turns out that trying to pretend that all three rewriting styles (string, term, graph) are the same thing "mostly works", but causes all kinds of friction, confusion, conundrums in detailed little corners. So, for example, BindLink was an early attempt to define a Lambda for declarative graphs. In many/most ways, it really is "just plain-old-lambda". It works, and works great to this day, but, never-the-less, we also created more stuff that is "just like lambda, but different", including LambdaLink, etc. In many ways, its an ongoing experiment. The search for "perfect" has more recently lead to "values", which are a lot like "valuations" in model theory. (and again, recall that model-theory is kind-of-ish like lambda-calculus, but its typed.) There's no "logic" in the atomspace, but you could add logic by using the URE, and/or by several other ways, including parsing, sheaves, and openpsi. In short, there's lots of different kinds of logic, and lots of different ways of implementing it, and we are weakly fiddling with several different approaches. And I have more in mind, but lacking in time. -- Linas -- cassette tapes - analog TV - film cameras - you -- You received this message because you are subscribed to the Google Groups "opencog" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/opencog. To view this discussion on the web visit https://groups.google.com/d/msgid/opencog/CAHrUA35V2Uk0YbwERPMkPhpxevriT0DZvaYzLtEPXUQC9TiUHQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
