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LeanPool.Lean4GlCoalgebras.Logic.Syntax

Syntax of Basic Modal Logic #

Here we supply basic definitions, abbreviations, and lemmas about the syntax of BML.

Type of BML Formulas.

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        @[reducible, inline]

        A sequent is a finite set of formulas, read disjunctively.

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          Auxiliary declaration used in the GL coalgebra development.

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            Auxiliary declaration used in the GL coalgebra development.

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              Auxiliary declaration used in the GL coalgebra development.

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                Auxiliary declaration used in the GL coalgebra development.

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                  Auxiliary declaration used in the GL coalgebra development.

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                    Auxiliary declaration used in the GL coalgebra development.

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                      Negation of a BML Formula.

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                        Auxiliary declaration used in the GL coalgebra development.

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                          Auxiliary declaration used in the GL coalgebra development.

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                            Auxiliary declaration used in the GL coalgebra development.

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                              Auxiliary declaration used in the GL coalgebra development.

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                                Basic operations and simp lemmas for Formulas #

                                Returns true if the formula is a propositional atom at n.

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                                  Returns true if the formula is a negated atom na n.

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                                    Returns true if the formula is a diamond formula φ.

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                                      Returns some φ if the formula is φ, otherwise none.

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                                        @[simp]

                                        Extracts φ from φ, given a proof that the formula is a diamond.

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                                          Returns true if the formula is a box formula φ.

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                                            theorem Lean4GlCoalgebras.Formula.neg_eq {φ ψ : Formula} :
                                            (~φ) = (~ψ) → φ = ψ

                                            Negation is injective.

                                            @[simp]

                                            Negation is involutive.

                                            Vocab of a BML Formula. Expressed as underlying natural numbers.

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                                              Atoms of a BML Formula. Expressed as underlying natural numbers.

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                                                Literals of a BML Formula. Expressed as underlying natural numbers.

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                                                  Get a fresh variable not occuring in a BML Formula.

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                                                    Fischer-Ladner closure of a BML Formula.

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                                                      Lemmas about FL Closure of BML Formulas #

                                                      Fischer-Ladner closure is reflexive.

                                                      theorem Lean4GlCoalgebras.Formula.FL_mon {φ ψ : Formula} (ψ_sub_φ : ψ φ.FL) :
                                                      ψ.FL φ.FL

                                                      Fischer-Ladner closure is monotone.

                                                      Basic operations and simp lemmas for Sequents #

                                                      Length of a sequent.

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                                                        Auxiliary declaration used in the GL coalgebra development.

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                                                          Auxiliary declaration used in the GL coalgebra development.

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                                                            Auxiliary declaration used in the GL coalgebra development.

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                                                              Auxiliary declaration used in the GL coalgebra development.

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                                                                Auxiliary declaration used in the GL coalgebra development.

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                                                                  Fischer-Ladner closure of a sequent.

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                                                                    Lemmas about FL Closure of Sequents #

                                                                    theorem Lean4GlCoalgebras.Sequent.FL_mon {Δ Γ : Sequent} (Δ_sub_Γ : Δ Γ) :
                                                                    Δ.FL Γ.FL
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                                                                    Auxiliary declaration used in the GL coalgebra development.

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                                                                      @[reducible, inline]

                                                                      Auxiliary declaration used in the GL coalgebra development.

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                                                                        Basic operations and simp lemmas for Split Sequents #

                                                                        Auxiliary declaration used in the GL coalgebra development.

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                                                                          @[irreducible]

                                                                          Auxiliary declaration used in the GL coalgebra development.

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                                                                            Lemmas about FL Closure of Split Formulas #

                                                                            Fischer-Ladner Closure is reflexive.

                                                                            theorem Lean4GlCoalgebras.SplitFormula.FL_mon {φ ψ : SplitFormula} (ψ_sub_φ : ψ φ.FL) :
                                                                            ψ.FL φ.FL

                                                                            Fischer-Ladner Closure is monotone.

                                                                            Lemmas about FL Closure of Split Sequents #

                                                                            Auxiliary declaration used in the GL coalgebra development.

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                                                                              Fischer-Ladner Closure is reflexive.

                                                                              theorem Lean4GlCoalgebras.SplitSequent.FL_mon {Δ Γ : SplitSequent} (Δ_sub_Γ : Δ Γ) :
                                                                              Δ.FL Γ.FL

                                                                              Fischer-Ladner Closure is monotone.

                                                                              Fischer-Ladner Closure is idempotent.

                                                                              Basic operations and simp lemmas for Split Sequents #

                                                                              Find underlying Sequent of a Split Sequent.

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                                                                                Auxiliary declaration used in the GL coalgebra development.

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                                                                                  Auxiliary declaration used in the GL coalgebra development.

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                                                                                    Auxiliary declaration used in the GL coalgebra development.

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                                                                                      Auxiliary declaration used in the GL coalgebra development.

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                                                                                        Properties of Substitutions #

                                                                                        theorem Lean4GlCoalgebras.single_neg (n : ) (φ ψ : Formula) :
                                                                                        single n ψ (~φ) = (~single n ψ φ)
                                                                                        theorem Lean4GlCoalgebras.single_imp (n : ) (C D E : Formula) :
                                                                                        single n C (~D v E) = (~single n C D v single n C E)
                                                                                        theorem Lean4GlCoalgebras.single_iff (n : ) (C D E : Formula) :
                                                                                        single n C ((~D v E)&~E v D) = ((~single n C D v single n C E)&~single n C E v single n C D)
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                                                                                        theorem Lean4GlCoalgebras.single_identity (n : ) (φ : Formula) :
                                                                                        single n (at n) φ = φ

                                                                                        Properties of Vocab #

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                                                                                        theorem Lean4GlCoalgebras.in_single_voc (m n : ) (φ ψ : Formula) :
                                                                                        mφ.vocab(m nmψ.vocab)nφ.vocabm(single n φ ψ).vocab
                                                                                        theorem Lean4GlCoalgebras.not_in_single_voc (n : ) (φ ψ : Formula) :
                                                                                        nφ.vocabsingle n ψ φ = φ
                                                                                        theorem Lean4GlCoalgebras.in_single_voc' {m n : } {φ ψ : Formula} :
                                                                                        m (single n φ ψ).vocabm φ.vocab n ψ.vocab m ψ.vocab m n

                                                                                        Some very specific lemmas about Finset.sum #

                                                                                        Ideally grind or aesop or some other tactic could sort out these simple helper lemmas, but I could not figure out how.

                                                                                        theorem Lean4GlCoalgebras.sub_add_left {n m l : } :
                                                                                        n + m = ln = l - m
                                                                                        theorem Lean4GlCoalgebras.lt_and_le_imp_add_lt {a b c : } :
                                                                                        b ac < ba - b + c < a
                                                                                        theorem Lean4GlCoalgebras.Finset.sum_diff_singleton_lt {α : Type} [DecidableEq α] {A C : Finset α} {b : α} {f : α} :
                                                                                        b AC.sum f < f b(A \ {b} C).sum f < A.sum f