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#P is closed under parsimonious reductions

Lax366625.SharpPClosure · concepts/Lax366625/SharpPClosure.lean · lax-366625

proven

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    Natural Language Statement

    Theorem

    Membership in #P travels backward along ordered parsimonious reductions and along relativized ordered parsimonious reductions: if a counting problem reduces to a problem of #P, it is in #P. The witnesses of the target, pulled back along the interpretation, are witnesses of the source; for a relativized reduction, the kernel pins the pulled relations to the definable domain, which makes the correspondence of witnesses a bijection. Membership reads a problem on its finite instances only.

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

    This concept declares 3 statements. Each proof establishes one of them relative to its assumptions.

    1 SharpP_mem_congr_finite proven

    2 SharpP_mem_of_orderedParsimonious proven

    3 SharpP_mem_of_relOrderedParsimonious 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 Lax535992.HornSat
    9import Lax535992.CircuitValue
    10import Lax535992.DeterministicMachines
    11import Lax535992.ClassPTIME
    12import Lax366625.CountingProblems
    13import Lax366625.CountingClasses
    14import Lax366625.WitnessCounting
    15import Lax366625.SecondOrderCounting
    16import Lax366625.QuantitativeLogic
    17import Lax366625.CountingSat
    18import Lax366625.MachineNumbers
    19import Lax366625.CountingRuns
    20import Lax366625.NumberedCircuits
    21import Lax366625.HornNumbers
    22
    23/-!
    24---
    25title: #P is closed under parsimonious reductions
    26type: theorem
    27---
    28Membership in #P travels backward along ordered parsimonious reductions and
    29along relativized ordered parsimonious reductions: if a counting problem
    30reduces to a problem of #P, it is in #P. The witnesses of the target, pulled
    31back along the interpretation, are witnesses of the source; for a
    32relativized reduction, the kernel pins the pulled relations to the definable
    33domain, which makes the correspondence of witnesses a bijection. Membership
    34reads a problem on its finite instances only.
    35-/
    36
    37namespace Lax366625.SharpPClosure
    38
    39open FirstOrder FirstOrder.Language
    40open Lax904597.Problems Lax904597.Interpretations Lax904597.Relativized Lax904597.SecondOrder
    41open Lax904597.Classes Lax904597.Sat Lax904597.Machines
    42open Lax535992.ClassPTIME
    43open Lax366625.CountingProblems Lax366625.CountingClasses Lax366625.WitnessCounting
    44open Lax366625.SecondOrderCounting
    45open Lax366625.QuantitativeLogic Lax366625.CountingSat Lax366625.MachineNumbers
    46open Lax366625.CountingRuns
    47open Lax366625.NumberedCircuits Lax366625.HornNumbers
    48
    49/-- Membership in SharpP travels backward along ordered parsimonious reductions. -/
    50axiom SharpP_mem_of_orderedParsimonious :
    51 ∀ {L L' : Language.{0, 0}} [L.IsRelational] [L'.IsRelational]
    52 {C : CountingProblem L} {D : CountingProblem L'},
    53 OrderedParsimoniousReduction C D → SharpP.Mem D → SharpP.Mem C
    54
    55/-- Membership in SharpP travels backward along relativized ordered
    56parsimonious reductions. -/
    57axiom SharpP_mem_of_relOrderedParsimonious :
    58 ∀ {L L' : Language.{0, 0}} [L.IsRelational] [L'.IsRelational]
    59 {C : CountingProblem L} {D : CountingProblem L'},
    60 RelOrderedParsimoniousReduction C D → SharpP.Mem D → SharpP.Mem C
    61
    62/-- Membership in SharpP only depends on the finite instances of a problem. -/
    63axiom SharpP_mem_congr_finite : ∀ {L : Language.{0, 0}} [L.IsRelational] {C D : CountingProblem L},
    64 (∀ (A : Type) [L.Structure A] [Finite A], C A = D A) → (SharpP.Mem C ↔ SharpP.Mem D)
    65
    66end Lax366625.SharpPClosure
    67
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