  In Positional-Slotted Object-Applicative (PSOA) RuleML, a predicate
application (atom) can have an Object IDentifier (OID) and descriptors that may
be positional arguments (tuples) or attribute-value pairs (slots). PSOA RuleML
explicitly specifies for each descriptor whether it is to be interpreted under
the perspective of the predicate in whose scope it occurs. This
predicate-dependency dimension refines the space between oidless, positional
atoms (relationships) and oidful, slotted atoms (framepoints): While
relationships use only a predicate-scope-sensitive (predicate-dependent) tuple
and framepoints use only predicate-scope-insensitive (predicate-independent)
slots, PSOA uses a systematics of orthogonal constructs also permitting atoms
with (predicate-)independent tuples and atoms with (predicate-)dependent slots.
This supports data and knowledge representation where a slot attribute can have
different values depending on the predicate. PSOA thus extends object-oriented
multi-membership and multiple inheritance. Based on objectification, PSOA laws
are given: Besides unscoping and centralization, the semantic restriction and
transformation of describution permits rescoping of one atom's independent
descriptors to another atom with the same OID but a different predicate. For
inheritance, default descriptors are realized by rules. On top of a metamodel
and a Grailog visualization, PSOA's atom systematics for facts, queries, and
rules is explained. The presentation and (XML-)serialization syntaxes of PSOA
RuleML are introduced. Its model-theoretic semantics is formalized by extending
the interpretation functions for dependent descriptors. The open-source
PSOATransRun system realizes PSOA RuleML by a translator to runtime predicates,
including for dependent tuples (prdtupterm) and slots (prdsloterm). Our tests
show efficiency advantages of dependent and tupled modeling.
