Glossary

This page answers: I see a term — what does it mean?

Terse one-line definitions. Cross-links to the chapter or RFD that gives the full treatment.

A

• ABox — the assertional layer. Facts about specific individuals (e.g., Person(alice)). Contrast with TBox. See ch02-02.
• AFT — Approximation Fixpoint Theory (Denecker, Marek, Truszczynski 2000). The bilattice-parametric framework Argon’s truth-value semantics is grounded in. Subsumes K3, FDE, Boolean, and every CWA variant under one algebraic structure. See RFD-0037.
• Aggregate — sum, count, min, max, avg over a body of atoms. May carry a where filter. See ch02-04.
• Anonymous individual — an individual created without an explicit name; identifier synthesized from content hash. See ch02-02.
• Anti-rigid — a metatype property: instances of an anti-rigid type can stop being instances over time without ceasing to exist (UFO’s roles, phases). Compare rigid.
• Argon — the language. The compiler is oxc. See the substrate chapter.
• Axiom — a structural rule attached to a concept or relation. See ch02-04.

B

• BFO — Basic Formal Ontology. A foundational ontology; loads as a peer package, not a built-in. See RFD-0002.
• Belnap-Dunn FDE — see FDE.
• Bilattice — an algebraic structure with two independent partial orders (truth and information) on the same carrier. Fitting (1991). The substrate Argon’s Truth4 realizes. See RFD-0037.
• Bivalent lockfile — a lockfile carrying both a content hash and a constructs-hash for each entry. See RFD-0013.
• Bitemporal — both valid time and transaction time. The kernel’s event log is bitemporal. See RFD-0021.

C

• Closed World Assumption (CWA) — the modeling assumption that absence of evidence is evidence of absence. Opposite of OWA. See RFD-0037 (which supersedes RFD-0016).
• Compute — a declarable item that returns a value at the call site. Three forms: expression, inline body, opaque Rust FFI. See RFD-0006.
• Concept — the language’s term for a class / type. Specializes other concepts via <:. See ch02-02.
• Constructs hash — a Merkle root over a package’s exported declaration signatures. Catches semantic identity. See RFD-0013.
• Content hash — byte-level hash of source. Catches byte identity. Pairs with constructs hash. See RFD-0013.
• CQRS — Command-Query Responsibility Segregation. Reads go through projections; writes append to the event log. See RFD-0022.

D

• Decidability tier — Argon’s graduated decidability ladder. Independent of OWL profiles. See RFD-0004.
• Decorator — a user-declared annotation that attaches algebraic / structural properties to relations. Lowers to a recognized shape. See ch02-01, RFD-0018.
• Defeasible — a rule whose conclusion can be overridden by a more specific rule. Default rule strength. Contrast strict.
• Derive — a rule that produces new facts from existing facts. Form: pub derive head(args) :- body. See ch02-04.
• Diagnostic — a compiler-emitted message (error, warning, info). Codes: OE / OW / OI. See Appendix C, RFD-0024.
• DRedc — Delete-Rederive with counting. The current IVM algorithm. See RFD-0022.

E

• Edition — an integer version of the source-syntax dialect. Parse-time only. See RFD-0012.
• Elaboration — the compiler phase that resolves names, type-checks, and produces Core IR. See oxc rustdoc on the elaborate module.
• Event log — ont.axiom_events, the kernel’s append-only assertion / retraction record. See RFD-0021.
• Exactly True Logic / ETL — Pietz & Rivieccio (2013). The four-valued logic where only T is designated. The rigorous published anchor for Argon’s “fail-closed on unknown” rule. See RFD-0037.
• Expect — a test block matching specific diagnostics or values against source markers. See ch03-03.

F

• FDE — First-Degree Entailment / Belnap-Dunn four-valued logic (Belnap 1977 / Dunn 1976). Truth values: T (told true), F (told false), N (told neither / unknown — Argon’s can), B (told both — Argon’s both). Argon’s storage substrate; cross-standpoint federated queries surface FDE values. See RFD-0037.
• Federation — aggregating per-standpoint query results across multiple standpoints via AFT info-join. Lifts K3 contributions into FDE outputs; BOTH arises exactly when sources disagree. See RFD-0037.
• Fixture — a test-local mini-module elaborated under capture mode. See ch03-03.
• Fork — a copy-on-write branch of the kernel’s event log. Supports hypothetical reasoning. See RFD-0021.
• Foundational ontology — a top-level conceptual scheme (UFO, BFO, DOLCE, GFO) that the package loads. The compiler privileges none. See RFD-0002.
• Frame — a reusable test-scaffolding declaration. Composes with using F. See ch03-03.
• Functor module — a module parameterized by other modules. See RFD-0009.

G

• GFO — General Formal Ontology. A foundational ontology; loads as a peer package.
• Group axiom — a structural declaration over multiple concepts (disjoint, complete, partition).

H

• Hypothetical — a speculative-reasoning block. Operates under a forked event log. See ch02-04.

I

• Inert — the property that the compiler privileges no specific foundational ontology. See RFD-0002.
• Intent node — what an AGENTS.md file is. Each declares the directory’s purpose and operating rules.
• IVM — Incremental View Maintenance. Algorithm class for keeping derived projections in sync with assertions. See RFD-0022.

K

• K3 — Kleene’s strong three-valued logic (Kleene 1952). Truth values: T (true), F (false), U (unknown). Argon’s per-standpoint refinement-membership lattice context; the consistent fragment of FDE. The conditional propagates U → U to U (versus Łukasiewicz Ł3 which makes it T). See RFD-0037.
• Kernel — the runtime (storage + reasoning + multitenancy). Per-tenant instances. See RFD-0020.
• Kernel API v2 — resource-oriented HTTP API at /api/v2/*. See RFD-0023.
• Kleene-Belnap — informal compound naming. K3 (the Argon lattice for refinement membership) is the consistent fragment of FDE motivated as in Belnap (1977)’s question-answering argument; the Pietz-Rivieccio “Exactly True” designation pins down “only T succeeds.” See RFD-0037.
• Kripke — modal-logic semantics. Argon’s box() / diamond() operators correspond to Kripke necessity / possibility.

M

• Metatype — a user-declared classification with axis assignments (e.g., UFO’s kind = { rigid, sortal, provides }). See ch02-01.
• Metaxis — a user-declared axis along which metatypes can take values. See ch02-01.
• Metarel — a user-declared kind of relation (e.g., UFO’s Mediation). See ch02-01.
• Module — a single .ar file. The package’s top-level module is prelude.ar. See RFD-0010.
• Mutation — a first-class declarable item that runs require / do / retract / emit / return clauses. See RFD-0007.

N

• Nous — the structural reasoner. Pure, synchronous, no I/O. See crates/nous rustdoc.

O

• Open World Assumption (OWA) — the modeling assumption that absence of evidence is not evidence of absence. Argon supports it; refinement under OWA is in $K3$ (Kleene strong three-valued); cross-standpoint federated queries lift to $\mathsf{FDE}$. See RFD-0037.
• OntoUML — a UML-derived modeling notation. Supported via ox-ontouml bridge. See RFD-0003.
• Overlay — per-tenant kernel state layered over the shared base. See RFD-0020.
• OWL — Web Ontology Language. A foreign format; supported via ox-owl bridge. Argon’s tier ladder is independent of OWL profiles. See RFD-0004, RFD-0003.
• Oxide — the toolchain that ships Argon. Internal identity; binaries are ox, oxc, ox-lsp, oxup.

P

• Pattern — a parameterized template that emits declarations. Either via pattern declaration or bespoke surface form (correlative_pair, part_whole). See RFD-0019.
• Phase — a UFO metatype: a temporary state of an instance (e.g., Adult, Employed). UFO-specific.
• PosBool(M) — the provenance encoding. DNF over assertion identifiers. Stored as a JSONB value field. See RFD-0022.
• pub — visibility modifier promoting a declaration to package-public. Default is module-internal. See RFD-0011.

Q

• Query — a first-class declarable item that retrieves facts matching a body pattern. Carries why-provenance. See RFD-0007.

R

• Relation — a multi-place predicate between concepts. Same as rel in source.
• Recognized shape — an algebraic structure (transitive, symmetric, …) the recognizer fast-paths via specialized algorithms. Inhabits the recognized tier. See RFD-0004.
• RFD — Request for Discussion. The form this monorepo records design rationale. See RFD-0001.
• Rigid — a metatype property: instances of a rigid type cannot stop being instances without ceasing to exist (UFO’s kinds, subkinds). Compare anti-rigid.
• Role — a UFO metatype: a relational role an individual plays (e.g., Customer, Employee). UFO-specific.

S

• Saturation — the fixpoint of applying derivation rules until no new facts are derivable.
• Sortal — a metatype property: instances of a sortal type carry their own identity criteria.
• Standpoint — a perspectival viewpoint in the knowledge base. First-class; arranged in a partial-order lattice. See RFD-0010.
• Strict — a rule strength: the rule’s conclusion is unconditional, cannot be overridden. Contrast defeasible.
• Substrate — the language’s foundational layer of declaration forms (metatype, metaxis, metarel, decorator). See ch02-01.
• Subkind — a UFO metatype: a sortal whose identity is inherited from a kind ancestor. UFO-specific.

T

• TBox — the terminological layer. Declarations of concepts, relations, properties. Contrast ABox.
• Test — a first-class declarable item containing assertions and expect blocks. See ch03-03, RFD-0008.
• Tier — Argon’s decidability classification. See decidability tier.
• Top type — the universal upper bound. Notation: ⊤ (with Top as ASCII alternate). See RFD-0017.
• Transaction time — when a fact was recorded in the system. Pairs with valid time for bitemporal queries. See RFD-0021.

U

• UFO — Unified Foundational Ontology. A foundational ontology; ships as a peer package, not a built-in. See RFD-0002.
• unsafe logic { ... } — the FOL escape hatch block. Inhabits tier:fol. See RFD-0018.
• unproven — a test attribute marking a theorem claim the system cannot mechanically verify. See RFD-0008.
• use — module import statement. Single-symbol Named or glob form. See RFD-0010.

V

• Valid time — when a fact was true in the modeled world. Pairs with transaction time. See RFD-0021.

W

• where clause — structural constraint clause in a concept body. See ch02-02, RFD-0018.
• Why-provenance — derivation provenance carried as a value field on every derived fact. See RFD-0007.
• Workspace — a multi-package directory with a shared lockfile and target/. See RFD-0013.