Question about LambdaLink

[Roman Treutlein]

Hello,

I just wanted to make sure my use of the LambdaLink inside the Lojban<->Atomese translator is correct.

One use case is the following:

EquivalenceLink

LambdaLink

VariableNode "1"

EvaluationLink

PredicateNode "pred"

ListLink (VariableNode "1")

LambdaLink

VariableNode "2"

ContextLink

VariableNode "2"

ConceptNode "Somthing" (Might be a EvaluationLink))

I use this to define the PredicateNode "pred" so as to apply to things in whiches context  "Something" is true.

Does this do what I want it to? If not is there a different way to do this?

regards

/roman

[Linas Vepstas]

That looks plausible, but I can't tell if that's really a PLN question, or if its something the evaluator is supposed to handle.

Right now, the evaluator ignores  EquivalenceLink, it only handles EqualLink and IdenticalLink.

When it evaluates this, it executes the two sides of the EqualLink, and compares the result of the execution.   What you have written is not executable, because there are no arguments supplied to either of the lambdas.

So, instead, you seem to have something that PLN is supposed to handle -- whenever it sees one side of the equivalence, it can replace it by the other side, during its search. Or something like that.   The semantics of what you want to have happen here is unclear.  What is supposed to happen?

Anything that strays outside of the bounds of what is explicitly mentioned on the wiki pages (i.e. http://wiki.opencog.org/w/LambdaLink) will almost surely result in errors or lead down code paths where nothing is implemented. 

--linas

/roman

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[Roman Treutlein]

Yes PLN is supposed to use this. In Lojban, there are so-called even-abstractors which take a relationship/sentence X and turn it into the predicate "arg1 is an event of X". This seems to be equivalent to saying "arg1 is a Context in which X happens/is true".

This way PLN should be able to "understand" what exactly this predicate means.

I might also want to use this to say that there are 2 equivalent Predicates but with changed argument orders.

/roman

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[Linas Vepstas]

Did you review this page:

http://wiki.opencog.org/wikihome/index.php/EquivalenceLink

Most of what is done there is done without the LambdaLink ... but then, that wiki page was written before LambdaLink existed, and the vairable scoping is implicitly assumed.

If you expect PLN to manipulate these structures, it would be wise to first test PLN, and see if they actually work as expected.  They may not .. they may be un-implemented.

 

[Nil Geisweiller]

Hi Roman,

this is compatible with PLN. I don't think all EquivalentLink PLN rules
are implemented, the main one, turning EquivalentLink to double
ImplicationLink is.

Nil

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