• README ⤓ .txt 2026-07-17T121634.146 000000000000736
  Logics of knowledge and belief, in which the operators read "agent i knows that" or "agent i believes that," interpreted over epistemic accessibility relations. Multi-agent settings add group notions—common and distributed knowledge—and the dynamics of how information changes.
• Action Model Logic ⤓ .md 2026-07-17T120407.600 000000000000824
  Baltag, Moss, Solecki (1998). General epistemic actions. Product update. Beyond announcements. Foundation of BMS framework.
• AGM Belief Revision ⤓ .md 2026-07-17T120407.600 000000000000832
  Alchourrón, Gärdenfors, Makinson (1985). Rational belief change. Contraction and revision. Postulates. Foundation of belief dynamics.
• Autoepistemic Logic ⤓ .md 2026-07-15T054406.000 000000000024488
  Robert Moore introduced autoepistemic logic (1985) to formalize reasoning about one's own beliefs. An ideally rational agent reasoning about what they know and don't know. Non-monotonic: "I don't believe P, so P is probably false." Related to default logic but based on belief rather than defaults. Foundation for introspective reasoning in AI.
• Awareness Logic ⤓ .md 2026-07-15T071017.000 000000000014712
  Fagin and Halpern (1988). Agents may be unaware of some propositions. Awareness function: what agent considers. Explicit vs implicit knowledge. Foundation for bounded reasoning.
• Belief Logic ⤓ .md 2026-07-15T063459.000 000000000018624
  Hintikka's epistemic logic extends to belief (1962). KD45 as standard doxastic logic. Weaker than knowledge: belief can be false. Introspection: beliefs about beliefs. Foundation for belief revision and multi-agent reasoning.
• Common Knowledge Logic ⤓ .md 2026-07-15T071016.000 000000000014624
  Lewis (1969), Aumann (1976). Knowledge shared by all and known to be shared. Fixed point: everyone knows everyone knows... Foundation for coordination and convention.
• Dynamic Doxastic Logic ⤓ .md 2026-07-17T120407.600 000000000000856
  Segerberg (1995), Baltag, Smets. Belief revision as action. Dynamic modalities. Plausibility models. Foundation of dynamic epistemics.
• Dynamic Epistemic Logic ⤓ .md 2026-07-15T055804.000 000000000021864
  Plaza introduced public announcement logic (1989). Baltag, Moss, and Solecki generalized to action models (1998). Van Benthem unified dynamic and epistemic traditions. Combines epistemic logic with dynamic updates. Models how knowledge changes through communication and observation.
• Epistemic Logic ⤓ .md 2026-07-15T052511.000 000000000029664
  Jaakko Hintikka's Knowledge and Belief (1962) established epistemic logic as a formal discipline. Builds on modal logic with knowledge and belief as modalities. Extended to multi-agent systems by Halpern, Moses, and others (1980s-1990s). Common knowledge formalized by David Lewis (1969) and Aumann (1976).
• Epistemic Temporal Logic ⤓ .md 2026-07-17T120407.600 000000000000872
  Combines epistemic and temporal logics (1980s-90s). Also called the temporal logic of knowledge. Halpern, van der Meyden, and Vardi developed foundations. Knowledge changes over time; time reveals information. Security protocols, distributed systems need both. Tools: MCK, MCMAS.
• Erotetic Logic ⤓ .md 2026-07-15T235811.000 000000000036656
  Nuel Belnap and Thomas Steel, The Logic of Questions and Answers (1976), building on Belnap's An Analysis of Questions (1963); Hamblin (1958) and Åqvist's imperative-epistemic reduction (1965) are the other founding lines. Andrzej Wiśniewski's The Posing of Questions (1995) and Questions, Inferences, and Scenarios (2013) give inferential erotetic logic, in which questions stand in consequence relations to each other.
• Justification Logic ⤓ .md 2026-07-15T054815.000 000000000026744
  Sergei Artemov introduced the Logic of Proofs (LP) in 1995, solving a long-standing problem about the intended provability semantics of intuitionistic logic. Extended to justification logic more broadly (2000s). Replaces the box □φ with explicit justifications t:φ ("t is a justification for φ"). Makes evidence explicit where modal logic leaves it implicit.
• Plausibility Logic ⤓ .md 2026-07-15T072409.000 000000000014808
  Friedman and Halpern (1995), Baltag and Smets (2008). Graded belief and plausibility. More/less plausible worlds. Dynamic belief revision. Foundation for epistemic plausibility.
• Probabilistic Epistemic Logic ⤓ .md 2026-07-15T063306.000 000000000019048
  Fagin and Halpern developed probabilistic epistemic reasoning (1994). Combines probability with knowledge. "Agent i assigns probability ≥ 0.8 to φ." Type spaces (Harsanyi). Foundation for Bayesian games and information economics.
• Public Announcement Logic ⤓ .md 2026-07-15T061754.000 000000000017808
  Plaza introduced PAL (1989). Simplest dynamic epistemic logic. Models truthful public announcements. Announces φ: eliminate worlds where φ false. Foundation for more complex epistemic updates. Extensively studied fragment of DEL.
• Topological Epistemology ⤓ .md 2026-07-17T120407.600 000000000000872
  McKinsey, Tarski (1940s), recent: Baltag, Bezhanishvili. Topology for knowledge. Open sets as evidence. Interior as knowable. Spatial epistemology.
• Topological Semantics ⤓ .md 2026-07-15T074051.000 000000000013968
  Tarski and McKinsey (1944). Modal logic via topology. Interior operator = necessity. Open sets = possible. Foundation for spatial modal logic.
• CRITERIA ⤓ .txt 2026-07-17T120407.600 000000000000752
  Boundary: Belief revision appears here (as doxastic modal logic) and in Applications/Knowledge (as postulate-based KR); the modal logic lives here, the AGM machinery there. Justification logic is cross-listed with Alethic. Probabilistic epistemic logics that foreground probability belong in Applications/Probabilistic. Topological semantics is cross-listed with Metatheory/Model-Theory.