Hi Alex, I'll try to be brief.
On Wed, May 10, 2017 at 2:20 PM, Alex <[email protected]> wrote: > Well - here was mentioned idea that Atomspace/Atomese can be perceived > like logical framework, like meta-logic in which every other kind of logic > can be encoded. Well - logic is deductive reasoning and deductive reasoning > is only one type of reasoning besides inductive, abductive and analogical > reasoning. So - maybe not just meta-logic but even more - meta-reasoning > system... > Reasoning, in any logical framework, can be accomplished by rule application. These rules are often called "axioms", depending on the textbook. As far as I know, there is little or no scholarly work on "meta-reasoning" or "meta-logic", and the reason for that is because the academic literature use a different set of words to talk about this. This includes "proof theory" and the related topics of topos theory, sheaf theory, type theory. A fun recent read on the topic is ludics from Jean-Yves Girard <https://en.wikipedia.org/wiki/Jean-Yves_Girard>. These are the things that are foundational to "meta-reasoning". But I was taken aback by the fact, that PLN (and NARS) currently is based > on Aristotelian term logic (just monadic fragment of the first order > predicate logic), > as I understand. I believe that PLN can be extended to full predicate logic > or even to more general logics, > I think you misunderstand. The word "term" being used here is not in the sense of "term logic", but in the sense of a "term" in logic, for example "term algebra", Term algebras underly things like "model theory", which in turn underlies logics of various sorts. https://en.wikipedia.org/wiki/Term_algebra The "atoms" in opencog are the same thing as the "atoms" in that wikipedia article. So, for example, these articles describe opencog atoms: https://en.wikipedia.org/wiki/Atomic_formula https://en.wikipedia.org/wiki/Atomic_sentence Opencog truth values are interpretations of structures, which are defined here: https://en.wikipedia.org/wiki/Structure_(mathematical_logic) https://en.wikipedia.org/wiki/Interpretation_(model_theory) https://en.wikipedia.org/wiki/Interpretation_(logic) For example, legal reasoning (of which I am fan) consists from the > commonsense reasoning which can be done in Atomspace but also it consists - > in special cases - from formal inference that should be done in specific > logics (e.g. deontic defeasible logics). > Sure you can do that. the atomspace doesn't care which logic you care to use. Just plug in the rules (axioms) that define deontic logic, add in some data, turn on the chainers, and off you go. *Is it possible to call external functions from the Atomspace? E.g. can Atomspace BindLink call external program in its rule head?* *Yes. RTFM* > > For the external reasoning system I have choosen Coq proof asistant (which > I am currently learning) which is capable of acting as meta-logic framework > and in which it is possible to encode wealth of logics > Yes, that's fine. you should learn coq. It will help you understand what some parts of opencog are like. Note, however, that the "interpretations of structures" that coq assigns are all crisp true/false boolean values. In the atomspace, and in the chainers, we allow arbitrary groupings of floating-point numbers. This allows us to model bayesian probabilities, among other things, which, to the best of my understanding, coq cannot do. Unfortunaltely, this means that the algorithms that underly coq, such as DPLL and SAT solvers, simply cannot be used for inference control in the opencog chainers. > There is long way to go before Atomspace can be used as strong meta-logic framework You only say that because you don't understand what the atomspace is. -- linas -- 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/CAHrUA37q5CeUsgrv-A-G2A%2B4O9f3dUpLWwSXbe4Yk%2BCSnF%2BerQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
