I updated the wiki page to mention it, and also mention that a BeliefLink is the same as EvaluationLink Predicate "belief". Not only would a port into the current PLN infratructure be useful, but that should be followed by a tutorial/example, and there should also be a hookup into the chatbot. That would ... make for a fun demo.
On Wed, Mar 15, 2017 at 11:40 AM, Ben Goertzel <[email protected]> wrote: > Hmm, OK, it's been a while since that work was done and almost as long > since I looked at it > > The crux of Sumit's work was to modify the PLN truth value formulas to > work sensibly for these modal-logic operators (belief, etc.). That > part was solid and I remember it. But the choice of link types he > used, I don't remember well and would need to revisit... probably > you're right that it needs revisiting... > > > > On Wed, Mar 15, 2017 at 11:36 AM, Linas Vepstas <[email protected]> > wrote: > > I just skimmed that code, and it does not seem to make use of the KR > > structures described in http://wiki.opencog.org/w/Claims_and_context > and > > instead invents new link types .. e.g. BeliefLink. This leads to a > > proliferation: you'd need BeliefLink, SayLink, > > TellLink,UseToBeleiveInThePastLink, LieLink etc. So its not just a > port, > > but a fairly serious restructuring. > > > > --linas > > > > On Wed, Mar 15, 2017 at 11:14 AM, Ben Goertzel <[email protected]> wrote: > >> > >> Code and theory for extending PLN to handle modal reasoning regarding > >> beliefs, knowledge and so forth is here: > >> > >> > >> https://github.com/sumitsourabh/opencog/tree/ > patch-1/opencog/reasoning/pln/rules/epistemic-reasoning > >> > >> This was carefully worked out by Sumit Sourabh and Matt Ikle' a few > years > >> ago. > >> > >> The code needs to be merged into the current version of PLN. This > >> would be a useful thing for someone to do, and then write associated > >> unit tests. > >> > >> -- Ben > >> > >> > >> On Wed, Mar 15, 2017 at 11:07 AM, Linas Vepstas <[email protected] > > > >> wrote: > >> > > >> > > >> > On Sat, Mar 11, 2017 at 10:25 PM, Alex <[email protected]> > >> > wrote: > >> >> > >> >> Hi! > >> >> > >> >> There can be modalities (which are usually expressed as diamonds or > >> >> boxes > >> >> (operators) in modal logic): > >> >> DUTY_TO_PERFORM_ACTION(agent, action, time horizone) - agent should > >> >> perform action within time horizon > >> >> BELIEF(agent, statement, time instant) - agent believes in statement > at > >> >> the time instant > >> > > >> > > >> > > >> > Wasn't this discussed in some other thread, just recently? > >> > EvaluationLinks are the standard way of representing knowledge in > >> > opencog. > >> > See wiki for that. > >> > > >> > Also see wiki about how to represent beleifs .. there is some section > >> > there > >> > that discuses this, I don't recall where, or what it said. > >> > > >> > We've had prior discussions on the mailing list about representing > >> > beleifs; > >> > but we only had a minimal discussion about reasoning over them. This > is > >> > one > >> > area that should be clearified, and if new PLN rules are needed to > >> > handle > >> > this, then now is a good time to figure that out. > >> > > >> > --linas > >> > > >> >> > >> >> > >> >> Such modalities are important in robotics (e.g. AGI safety - what > >> >> duties > >> >> and permissions robots have) and in communication (modelling other > >> >> agent > >> >> believes, knowledge and reasoning styles). > >> >> > >> >> Important point is, that by introducing modalities we also introduce > >> >> additional axioms/meta-rules that connect modal statements > (statements > >> >> under > >> >> modal operator) with the nonmodal statements and with the statements > of > >> >> other modalities (modal conversion). Example list of such metarules > are > >> >> available in https://en.wikipedia.org/wiki/Modal_logic. Such > metarules > >> >> sometimes are debatable, e.g. rule in deontic logic: > >> >> DUTY_TO_PERORM_ACTION(agent, > >> >> action)->PERMISSION_TO_PERFORM_ACTION(agent, > >> >> action) and such metarules sometimes lead to paradoxes (classical > >> >> deontic > >> >> logic is full of them), nevertheless, such metarules expresses > >> >> additional > >> >> knowledge about reality. And such metarules can be mined and used for > >> >> constraining inference process (inference control)! > >> >> > >> >> I have two questions regarding expression of modalities in OpenCog?: > >> >> 1) how we can express modalities in Scheme/atomspace? > >> >> -- One solution is to introduce new link types. Is such introduction > >> >> possible? Maybe OpenCog have GenericLink for which the user form > >> >> derivation > >> >> and for the derivation the user can define syntax (how many Nodes and > >> >> of > >> >> what Type are allowed in the new Link) and semantics (what processes > >> >> are > >> >> done, what is output and strenght values of the output)? I have not > >> >> heard > >> >> about such option; > >> >> -- Another solution is to use PredicateNode, e.g. belief can be > >> >> expressed: > >> >> PredicateNode "agent_believe" > >> >> ConceptNode "Erving" > >> >> ConceptNode "Door is open" > >> >> The question is - can be use other Node, Link, result of > >> >> SatisfyingSetLink > >> >> etc. in place of the literal "agent_believes"? Or we are bounded for > >> >> using > >> >> literal constants in the PredicateNode? If former is true, then the > >> >> system > >> >> is open for the arbitrary set of modalities and the system can > generate > >> >> new > >> >> modalities! > >> >> > >> >> 2) how we can express metarules for modalities in OpenCog?: > >> >> My proposal is to use rules that accepts some patterns of predicates > >> >> and > >> >> that generates new predicates: > >> >> > >> >> > >> >> rule_body(obligation_predicate_type_nodes)->rule_ > head(new_permission_predicate_type_nodes) > >> >> Again - the question is about flexibility of the system: is the > system > >> >> allows generation of new link types or new predicate then the system > >> >> can > >> >> mine/generate the relevant rules for the newly generate modalities! > >> >> > >> >> Of course, I am studying literature, experimenting, thinking about > >> >> this, > >> >> but maybe someone also has thought about those questions and has > >> >> already > >> >> something done - it would be nice to hear thoughts, proposals and > >> >> experience! > >> >> > >> >> Thanks! > >> >> > >> >> -- > >> >> 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/f70e8da1-1147- > 41e9-8aa6-c2acbab14ce6%40googlegroups.com. > >> >> For more options, visit https://groups.google.com/d/optout. > >> > > >> > > >> > -- > >> > 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/CAHrUA36r01Q% > 3DKbXsJE3%2BS2KbpfQ3oZ5WD%2B-XY_dfPP6PCPhdEw%40mail.gmail.com. > >> > > >> > For more options, visit https://groups.google.com/d/optout. > >> > >> > >> > >> -- > >> Ben Goertzel, PhD > >> http://goertzel.org > >> > >> “Our first mothers and fathers … were endowed with intelligence; they > >> saw and instantly they could see far … they succeeded in knowing all > >> that there is in the world. When they looked, instantly they saw all > >> around them, and they contemplated in turn the arch of heaven and the > >> round face of the earth. … Great was their wisdom …. They were able to > >> know all.... > >> > >> But the Creator and the Maker did not hear this with pleasure. … ‘Are > >> they not by nature simple creatures of our making? Must they also be > >> gods? … What if they do not reproduce and multiply?’ > >> > >> Then the Heart of Heaven blew mist into their eyes, which clouded > >> their sight as when a mirror is breathed upon. Their eyes were covered > >> and they could see only what was close, only that was clear to them.” > >> > >> — Popol Vuh (holy book of the ancient Mayas) > >> > >> -- > >> 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/CACYTDBdLatMo% > 2BSErmaU6g2An1YfiqmNcPBN_ru-MNcFwxxY6Eg%40mail.gmail.com. > >> For more options, visit https://groups.google.com/d/optout. > > > > > > -- > > 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/CAHrUA34BEp9WsoTMMw44nT-%3DCv% > 2BQE1i9%3D2bRg-NvSmEsekzy1g%40mail.gmail.com. > > > > For more options, visit https://groups.google.com/d/optout. > > > > -- > Ben Goertzel, PhD > http://goertzel.org > > “Our first mothers and fathers … were endowed with intelligence; they > saw and instantly they could see far … they succeeded in knowing all > that there is in the world. When they looked, instantly they saw all > around them, and they contemplated in turn the arch of heaven and the > round face of the earth. … Great was their wisdom …. They were able to > know all.... > > But the Creator and the Maker did not hear this with pleasure. … ‘Are > they not by nature simple creatures of our making? Must they also be > gods? … What if they do not reproduce and multiply?’ > > Then the Heart of Heaven blew mist into their eyes, which clouded > their sight as when a mirror is breathed upon. Their eyes were covered > and they could see only what was close, only that was clear to them.” > > — Popol Vuh (holy book of the ancient Mayas) > > -- > 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/CACYTDBevfrcxtXTr3XkPHL5P9OaG2Jnrc5-oKyJXJ8CBTn0i%2Bg% > 40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. > -- 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/CAHrUA35e5m6yo6iSXsYLEBaLB5NJOEb6b02%2B57XxLJbkZ3BweQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
