TruthValueOfLink
From OpenCog
The TruthValueOfLink is a ValueOfLink that returns the TruthValue associated to some atom. It must have the format:
TruthValueOfLink SomeAtom
On execution, it returns the TruthValue attached to SomeAtom. If SomeAtom is a evaluatable link type, it is evaluated first, so as to obtain a current TruthValue.
Individual components of the TruthValue can be accessed with the StrengthOfLink and the ConfidenceOfLink.
The TruthValueOfLink is primarily used in PredicateFormulaLinks, which allow truth-value formulas to be specified in Atomese.
Examples
Set a truth value, then fetch it:
(use-modules (opencog) (opencog exec)) (Concept "A" (stv 0.8 0.3)) (cog-execute! (TruthValueOf (Concept "A")))
Arithmetic computations are possible with the returned values:
(cog-execute! (Minus (Number 1) (TruthValueOf (Concept "A"))))
Component access is possible with the StrengthOf and ConfidenceOf links:
(cog-execute! (StrengthOf (Concept "A"))) (cog-execute! (ConfidenceOf (Concept "A")))
