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Invariance and characterization of HORN-SAT

Lax535992.HornSatInvariance · concepts/Lax535992/HornSatInvariance.lean · lax-535992

proven

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    Natural Language Statement

    Lemma

    Being a satisfiable Horn instance is invariant under isomorphism of CNF instances, and an instance is a yes-instance of HORN-SAT exactly when it is Horn and satisfiable.

    Concept map
    24 concepts
    100%
    Proven claimDefinitionThis conceptRelated conceptA → B: B builds on A
    Evidence

    This concept declares 2 statements. Each proof establishes one of them relative to its assumptions.

    1 hornSat_iff proven

    2 hornSatisfiable_iso proven

    Lean source view on GitHub

    1import Lax904597.Problems
    2import Lax904597.Interpretations
    3import Lax904597.Relativized
    4import Lax904597.SecondOrder
    5import Lax904597.Classes
    6import Lax904597.Sat
    7import Lax904597.Machines
    8import Lax485149.Problems
    9import Lax485149.Complement
    10import Lax485149.SecondOrderAtoms
    11import Lax485149.TransitiveClosure
    12import Lax485149.DeterministicTransitiveClosure
    13import Lax485149.ClassNL
    14import Lax485149.ClassL
    15import Lax535992.HornFragment
    16import Lax535992.LeastFixedPoint
    17import Lax535992.InflationaryFixedPoint
    18import Lax535992.HornSat
    19import Lax535992.CircuitValue
    20import Lax535992.Game
    21import Lax535992.DeterministicMachines
    22import Lax535992.ClassPTIME
    23
    24/-!
    25---
    26title: Invariance and characterization of HORN-SAT
    27type: lemma
    28---
    29Being a satisfiable Horn instance is invariant under isomorphism of CNF
    30instances, and an instance is a yes-instance of HORN-SAT exactly when it is
    31Horn and satisfiable.
    32-/
    33
    34namespace Lax535992.HornSatInvariance
    35
    36open FirstOrder FirstOrder.Language
    37open Lax904597.Problems Lax904597.Interpretations Lax904597.Relativized Lax904597.SecondOrder
    38open Lax904597.Classes Lax904597.Sat Lax904597.Machines
    39open Lax485149.Problems Lax485149.Complement Lax485149.SecondOrderAtoms
    40open Lax485149.TransitiveClosure Lax485149.DeterministicTransitiveClosure
    41open Lax485149.ClassNL Lax485149.ClassL
    42open Lax535992.HornFragment Lax535992.LeastFixedPoint Lax535992.InflationaryFixedPoint
    43open Lax535992.HornSat Lax535992.CircuitValue Lax535992.Game Lax535992.DeterministicMachines
    44open Lax535992.ClassPTIME
    45
    46/-- Being Horn and satisfiable is isomorphism-invariant. -/
    47axiom hornSatisfiable_iso : ∀ {A B : Type} [sat.Structure A] [sat.Structure B],
    48 (A ≃[sat] B) → (HornSatisfiable A ↔ HornSatisfiable B)
    49
    50/-- The yes-instances of HORN-SAT are exactly the instances with the defining
    51property. -/
    52axiom hornSat_iff : ∀ (A : Type) [sat.Structure A], HORNSAT A ↔ HornSatisfiable A
    53
    54end Lax535992.HornSatInvariance
    55
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