Documentation

Pdl.Tableau

PDL-Tableaux (Section 4) #

Projections #

Equations
Instances For
    Equations
    Instances For
      @[simp]
      theorem proj {A : } {X : List Formula} {g : Formula} :

      Loading and Loaded Histories #

      @[reducible, inline]
      abbrev History :

      A history is a list of Sequents. This only tracks "big" steps, hoping we do not need steps within a local tableau. The head of the first list is the newest Sequent.

      Equations
      Instances For
        def rep (Hist : History) (X : Sequent) :

        We have a repeat iff the history contains a node that is setEqTo the current node.

        Equations
        Instances For
          instance instDecidableRep {H : History} {X : Sequent} :
          Equations
          def LoadedPathRepeat (Hist : History) (X : Sequent) :

          A lpr means we can go k steps back in the history to reach an equal node, and all nodes on the way are loaded. Note: k=0 means the first element of Hist is the companion.

          Equations
          Instances For
            theorem LoadedPathRepeat.to_rep {Hist : History} {X : Sequent} (lpr : LoadedPathRepeat Hist X) :
            rep Hist X

            If there is any loaded path repeat, then we can compute one. FIXME There is probably a more elegant way, avoiding Nonempty and Fin.find. Something like: def getLPR (H : History) (X : Sequent) : Option ... := ... that might also give us uniqueness of LPRs?

            Equations
            • One or more equations did not get rendered due to their size.
            Instances For
              theorem LoadedPathRepeat_comp_isLoaded {Hist : History} {X : Sequent} (lpr : LoadedPathRepeat Hist X) :
              (List.get Hist lpr).isLoaded = true

              The PDL rules #

              inductive PdlRule (X Y : Sequent) :

              A rule to go from X to Y. Note the four variants of the modal rule.

              Instances For
                def instDecidableEqPdlRule.decEq {X✝ Y✝ : Sequent} (x✝ x✝¹ : PdlRule X✝ Y✝) :
                Decidable (x✝ = x✝¹)
                Instances For
                  inductive Tableau :

                  The Tableau [parent, grandparent, ...] child type.

                  A closed tableau for X is either of:

                  • a local tableau for X followed by closed tableaux for all end nodes,
                  • a PDL rule application
                  • a successful loaded repeat (MB condition six)
                  Instances For
                    def Tableau.size {Hist : History} {X : Sequent} :
                    Tableau Hist X
                    Equations
                    Instances For
                      theorem Tableau.size_next_lt_of_loc {a✝ : History} {a✝¹ : Sequent} {tab : Tableau a✝ a✝¹} {nrep : ¬rep a✝ a✝¹} {nbas : ¬a✝¹.basic} {lt : LocalTableau a✝¹} {next : (Y : Sequent) → Y endNodesOf ltTableau (a✝¹ :: a✝) Y} (tab_def : tab = loc nrep nbas lt next) (Y : Sequent) (Y_in : Y endNodesOf lt) :
                      (next Y Y_in).size < tab.size
                      theorem Tableau.size_next_lt_of_pdl {a✝ : History} {a✝¹ : Sequent} {tab : Tableau a✝ a✝¹} {nrep : ¬rep a✝ a✝¹} {bas : a✝¹.basic} {Y✝ : Sequent} {r : PdlRule a✝¹ Y✝} {next : Tableau (a✝¹ :: a✝) Y✝} (tab_def : tab = pdl nrep bas r next) :
                      next.size < tab.size
                      instance instDecidableExistsEndNodeOf {X : Sequent} {lt : LocalTableau X} {f : (Y : Sequent) → Y endNodesOf ltProp} {dec : (Y : Sequent) → (Y_in : Y endNodesOf lt) → Decidable (f Y Y_in)} :
                      Decidable (∃ (Y : Sequent) (Y_in : Y endNodesOf lt), f Y Y_in)
                      Equations
                      • One or more equations did not get rendered due to their size.
                      @[irreducible]
                      instance Tableau.instDecidableEq {Hist : History} {X : Sequent} {tab1 tab2 : Tableau Hist X} :
                      Decidable (tab1 = tab2)
                      Equations
                      • One or more equations did not get rendered due to their size.
                      def Tableau.isLrep {Hist : History} {X : Sequent} :
                      Tableau Hist XProp
                      Equations
                      Instances For
                        inductive provable :
                        Instances For

                          A Sequent is inconsistent if there exists a closed tableau for it.

                          Equations
                          Instances For

                            A Sequent is consistent iff it is not inconsistent.

                            Equations
                            Instances For