Arriving from another system

• Covers: which orientation page to read if you already think in Cyc, answer set programming, Prolog or Datalog, or a production rule engine — and the handful of facts that hold whatever you arrived from.
• Not here: the engine. Every line below routes to the page that owns it, and the map for a reader with no prior is README.md.
• Assumes: nothing. The vocabulary is glossary.md and the model is the README.

Pick your arrival

coming from	the page	the first thing that will surprise you
OpenCyc or ResearchCyc	from-cyc.md	there is no everything-context to assert into; scope is a property of the read
answer set programming	from-asp.md	there is no grounding step, and belief is a single labeling rather than a set of models
Prolog or Datalog	from-prolog.md	Foo is an individual and ?x is the variable — capitalization means nearly the opposite
CLIPS, Jess or Drools	from-production-rules.md	a rule concludes a sentence; there is no right-hand side to act in

What holds whatever you arrived from

• A sentence is not knowledge until it has a context. The unit is a sentex — sentence plus context — every sentex is in exactly one, and a read sees up the genlCx cone from wherever it asks → contexts.md
• A symbol's role is read off its spelling, and assert refuses a sentence that breaks the convention: parentOf a predicate, Fido an individual, physical_object a type, CxCore a context → naming.md
• A rule is a sentex too — same structure, same handle, same truth maintenance, additionally indexed by its antecedent and consequent predicates. So it is retractable, believable and askable-about, which is not true of a rule kept in a separate program → inference.md
• A stored sentex is not a believed one. Belief is computed from current state by a truth maintenance system, never accumulated, and matching, the taxonomy closures and the cached relations all follow it → nmtms.md
• Content is asserted defeasible unless you say otherwise. :default is the default and is what most common-sense knowledge wants; :monotonic is known-true and never defeasible. Two classes, and there is no third → nmtms.md
• Reading is a stack, not a function. Eight named levels sit between a raw index read and full backchaining, and query, prove, ask and sentexes-matching enter it at different heights → levels.md, api.md

Four properties hold across all of it, and the README's model section states them: order independence, locality, context scoping, and belief filtering. They are worth reading before the page for your own arrival, because most of the surprises below are one of the four showing through.

What these pages are not

They are one-way orientation, not a compatibility claim. A shared name usually covers a different semantics, and each page's third column is where that is said. Nothing here promises a program from the other system will run, or that a translation preserves what it meant.

They are also not an import route. No reader for a foreign format ships in this repository — a bridge is a plugin that declares itself in one edn resource on the classpath, and reading a corpus in is a separate task from writing for this engine → foreign.md, kbs.md.