X-Git-Url: http://git.megacz.com/?p=coq-hetmet.git;a=blobdiff_plain;f=src%2FHaskProof.v;h=46009f85b30468fb5dfe5e5d21604989d664a0ca;hp=87dfe2ee7d5e727a29fe0fc12d4d7203b9e3618b;hb=c90b598203ef23bf8d44d6b5b4a5a4b5901039cf;hpb=112daf37524662d6d2267d3f7e50ff3522683b8f

diff --git a/src/HaskProof.v b/src/HaskProof.v
index 87dfe2e..46009f8 100644
--- a/src/HaskProof.v
+++ b/src/HaskProof.v
@@ -10,11 +10,15 @@ Generalizable All Variables.
 Require Import Preamble.
 Require Import General.
 Require Import NaturalDeduction.
+Require Import NaturalDeductionContext.
 Require Import Coq.Strings.String.
 Require Import Coq.Lists.List.
-Require Import HaskGeneral.
+Require Import HaskKinds.
+Require Import HaskCoreTypes.
 Require Import HaskLiterals.
+Require Import HaskTyCons.
 Require Import HaskStrongTypes.
+Require Import HaskWeakVars.
 
 (* A judgment consists of an environment shape (Γ and Δ) and a pair of trees of leveled types (the antecedent and succedent) valid
  * in any context of that shape.  Notice that the succedent contains a tree of types rather than a single type; think
@@ -25,114 +29,139 @@ Inductive Judg  :=
   mkJudg :
   forall Γ:TypeEnv,
   forall Δ:CoercionEnv Γ,
-  Tree ??(LeveledHaskType Γ) ->
-  Tree ??(LeveledHaskType Γ) ->
+  Tree ??(LeveledHaskType Γ ★) ->
+  Tree ??(HaskType Γ ★) ->
+  HaskLevel Γ ->
   Judg.
-  Notation "Γ > Δ > a '|-' s" := (mkJudg Γ Δ a s) (at level 52, Δ at level 50, a at level 52, s at level 50).
-
-(* A Uniform Judgment (UJudg) has its environment as a type index; we'll use these to distinguish proofs that have a single,
- * uniform context throughout the whole proof.  Such proofs are important because (1) we can do left and right context
- * expansion on them (see rules RLeft and RRight) and (2) they will form the fiber categories of our fibration later on *)
-Inductive UJudg (Γ:TypeEnv)(Δ:CoercionEnv Γ) :=
-  mkUJudg :
-  Tree ??(LeveledHaskType Γ) ->
-  Tree ??(LeveledHaskType Γ) ->
-  UJudg Γ Δ.
-  Notation "Γ >> Δ > a '|-' s" := (mkUJudg Γ Δ a s) (at level 52, Δ at level 50, a at level 52, s at level 50).
-  Notation "'ext_tree_left'"    := (fun ctx j => match j with mkUJudg t s => mkUJudg _ _ (ctx,,t)  s end).
-  Notation "'ext_tree_right'"   := (fun ctx j => match j with mkUJudg t s => mkUJudg _ _ (t,,ctx) s end).
-
-(* we can turn a UJudg into a Judg by simply internalizing the index *)
-Definition UJudg2judg {Γ}{Δ}(ej:@UJudg Γ Δ) : Judg :=
-  match ej with mkUJudg t s => Γ > Δ > t |- s end.
-  Coercion UJudg2judg : UJudg >-> Judg.
+  Notation "Γ > Δ > a '|-' s '@' l" := (mkJudg Γ Δ a s l) (at level 52, Δ at level 50, a at level 52, s at level 50, l at level 50).
 
 (* information needed to define a case branch in a HaskProof *)
-Record ProofCaseBranch {n}{tc:TyCon n}{Γ}{lev}{branchtype : HaskType Γ}{avars} :=
-{ cbi_cbi              :  @StrongAltConInContext n tc Γ avars
-; cbri_freevars        :  Tree ??(LeveledHaskType Γ)
-; cbri_judg            := cbi_Γ cbi_cbi > cbi_Δ  cbi_cbi
-                          > (mapOptionTree weakLT' cbri_freevars),,(unleaves (vec2list (cbi_types cbi_cbi)))
-                          |- [weakLT' (branchtype @@ lev)]
+Record ProofCaseBranch {tc:TyCon}{Γ}{Δ}{lev}{branchtype : HaskType Γ ★}{avars}{sac:@StrongAltCon tc} :=
+{ pcb_freevars       :  Tree ??(LeveledHaskType Γ ★)
+; pcb_judg           := sac_gamma sac Γ > sac_delta sac Γ avars (map weakCK' Δ)
+                > (mapOptionTree weakLT' pcb_freevars),,(unleaves (map (fun t => t@@weakL' lev)
+                  (vec2list (sac_types sac Γ avars))))
+                |- [weakT' branchtype ] @ weakL' lev
 }.
 Implicit Arguments ProofCaseBranch [ ].
 
-(* Figure 3, production $\vdash_E$, Uniform rules *)
-Inductive URule {Γ}{Δ} : Tree ??(UJudg Γ Δ) -> Tree ??(UJudg Γ Δ) -> Type :=
-| RCanL   : ∀ t a        ,                          URule  [Γ>>Δ>    [],,a   |- t         ]      [Γ>>Δ>       a   |- t           ]
-| RCanR   : ∀ t a        ,                          URule  [Γ>>Δ>    a,,[]   |- t         ]      [Γ>>Δ>       a   |- t           ]
-| RuCanL  : ∀ t a        ,                          URule  [Γ>>Δ>       a    |- t         ]      [Γ>>Δ>  [],,a    |- t           ]
-| RuCanR  : ∀ t a        ,                          URule  [Γ>>Δ>       a    |- t         ]      [Γ>>Δ>  a,,[]    |- t           ]
-| RAssoc  : ∀ t a b c    ,                          URule  [Γ>>Δ>a,,(b,,c)   |- t         ]      [Γ>>Δ>(a,,b),,c  |- t           ]
-| RCossa  : ∀ t a b c    ,                          URule  [Γ>>Δ>(a,,b),,c   |- t         ]      [Γ>>Δ> a,,(b,,c) |- t           ]
-| RLeft   : ∀ h c x      ,             URule h c -> URule (mapOptionTree (ext_tree_left  x) h) (mapOptionTree (ext_tree_left  x) c)
-| RRight  : ∀ h c x      ,             URule h c -> URule (mapOptionTree (ext_tree_right x) h) (mapOptionTree (ext_tree_right x) c)
-| RExch   : ∀ t a b      ,                          URule  [Γ>>Δ>   (b,,a)   |- t         ]      [Γ>>Δ>  (a,,b)   |- t           ]
-| RWeak   : ∀ t a        ,                          URule  [Γ>>Δ>       []   |- t         ]      [Γ>>Δ>       a   |- t           ]
-| RCont   : ∀ t a        ,                          URule  [Γ>>Δ>  (a,,a)    |- t         ]      [Γ>>Δ>       a   |- t           ].
-
-
 (* Figure 3, production $\vdash_E$, all rules *)
 Inductive Rule : Tree ??Judg -> Tree ??Judg -> Type :=
 
-| RURule  : ∀ Γ Δ h c,                  @URule Γ Δ h c -> Rule (mapOptionTree UJudg2judg h) (mapOptionTree UJudg2judg c)
+| RArrange  : ∀ Γ Δ Σ₁ Σ₂ Σ l,       Arrange Σ₁ Σ₂ -> Rule [Γ > Δ > Σ₁     |- Σ            @l]   [Γ > Δ > Σ₂    |- Σ            @l]
 
 (* λ^α rules *)
-| RBrak : ∀ Γ Δ t v Σ l,                              Rule [Γ > Δ > Σ      |- [t  @@ (v::l) ]]   [Γ > Δ > Σ     |- [<[v|-t]>   @@l]]
-| REsc  : ∀ Γ Δ t v Σ l,                              Rule [Γ > Δ > Σ      |- [<[v|-t]> @@ l]]   [Γ > Δ > Σ     |- [t  @@ (v::l)  ]]
+| RBrak : ∀ Γ Δ t v Σ l,                              Rule [Γ > Δ > Σ      |- [t]@(v::l)     ]   [Γ > Δ > Σ     |- [<[v|-t]>   ] @l]
+| REsc  : ∀ Γ Δ t v Σ l,                              Rule [Γ > Δ > Σ     |- [<[v|-t]>   ] @l]   [Γ > Δ > Σ     |- [t]@(v::l)      ]
 
 (* Part of GHC, but not explicitly in System FC *)
-| RNote   : ∀ h c,                Note ->             Rule  h                                    [ c ]
-| RLit    : ∀ Γ Δ v       l,                          Rule  [                                ]   [Γ > Δ > []|- [literalType v @@ l]]
+| RNote   : ∀ Γ Δ Σ τ l,          Note ->             Rule [Γ > Δ > Σ      |- [τ        ]  @l]   [Γ > Δ > Σ     |- [τ          ] @l]
+| RLit    : ∀ Γ Δ v       l,                          Rule [                                 ]   [Γ > Δ > []|- [literalType v ]  @l]
 
 (* SystemFC rules *)
-| RVar    : ∀ Γ Δ σ       l,                          Rule [                                 ]   [Γ>Δ> [σ@@l]   |- [σ          @@l]]
-| RLam    : ∀ Γ Δ Σ tx te l,     Γ ⊢ᴛy tx : ★      -> Rule [Γ>Δ> Σ,,[tx@@l]|- [te@@l]        ]   [Γ>Δ>    Σ     |- [tx--->te   @@l]]
-| RCast   : ∀ Γ Δ Σ σ τ γ l,     Δ ⊢ᴄᴏ γ  : σ ∼ τ  -> Rule [Γ>Δ> Σ         |- [σ@@l]         ]   [Γ>Δ>    Σ     |- [τ          @@l]]
-| RBindingGroup  : ∀ Γ Δ Σ₁ Σ₂ τ₁ τ₂ ,   Rule ([Γ > Δ > Σ₁ |- τ₁ ],,[Γ > Δ > Σ₂ |- τ₂ ])         [Γ>Δ>  Σ₁,,Σ₂  |- τ₁,,τ₂          ]
-| RApp           : ∀ Γ Δ Σ₁ Σ₂ tx te l,  Rule ([Γ>Δ> Σ₁       |- [tx--->te @@l]],,[Γ>Δ> Σ₂ |- [tx@@l]])  [Γ>Δ> Σ₁,,Σ₂ |- [te   @@l]]
-| RLet           : ∀ Γ Δ Σ₁ Σ₂ σ₁ σ₂ l,  Rule ([Γ>Δ> Σ₁,,[σ₂@@l] |- [σ₁@@l] ],,[Γ>Δ> Σ₂ |- [σ₂@@l]])     [Γ>Δ> Σ₁,,Σ₂ |- [σ₁   @@l]]
-| REmptyGroup    : ∀ Γ Δ ,               Rule [] [Γ > Δ > [] |- [] ]
-| RAppT   : ∀ Γ Δ Σ κ σ τ l,     Γ ⊢ᴛy τ  : κ      -> Rule [Γ>Δ> Σ   |- [HaskTAll κ σ @@l]]      [Γ>Δ>    Σ     |- [substT σ τ @@l]]
+| RVar    : ∀ Γ Δ σ       l,                          Rule [                                 ]   [Γ>Δ> [σ@@l]   |- [σ          ] @l]
+| RGlobal : forall Γ Δ l   (g:Global Γ) v,            Rule [                                 ]   [Γ>Δ>     []   |- [g v        ] @l]
+| RLam    : forall Γ Δ Σ (tx:HaskType Γ ★) te l,      Rule [Γ>Δ> Σ,,[tx@@l]|- [te]         @l]   [Γ>Δ>    Σ     |- [tx--->te   ] @l]
+| RCast   : forall Γ Δ Σ (σ₁ σ₂:HaskType Γ ★) l,
+                   HaskCoercion Γ Δ (σ₁∼∼∼σ₂) ->      Rule [Γ>Δ> Σ         |- [σ₁]         @l]   [Γ>Δ>    Σ     |- [σ₂         ] @l]
+
+| RJoin  : ∀ Γ Δ Σ₁ Σ₂ τ₁ τ₂ l,   Rule ([Γ > Δ > Σ₁ |- τ₁ @l],,[Γ > Δ > Σ₂ |- τ₂ @l])         [Γ>Δ>  Σ₁,,Σ₂  |- τ₁,,τ₂       @l ]
+
+(* order is important here; we want to be able to skolemize without introducing new AExch'es *)
+| RApp           : ∀ Γ Δ Σ₁ Σ₂ tx te l,  Rule ([Γ>Δ> Σ₁ |- [tx--->te]@l],,[Γ>Δ> Σ₂ |- [tx]@l])  [Γ>Δ> Σ₁,,Σ₂ |- [te]@l]
+
+| RLet           : ∀ Γ Δ Σ₁ Σ₂ σ₁ σ₂ l,  Rule ([Γ>Δ> Σ₁ |- [σ₁]@l],,[Γ>Δ> [σ₁@@l],,Σ₂ |- [σ₂]@l ])     [Γ>Δ> Σ₁,,Σ₂ |- [σ₂   ]@l]
+| RWhere         : ∀ Γ Δ Σ₁ Σ₂ Σ₃ σ₁ σ₂ l,  Rule ([Γ>Δ> Σ₁,,([σ₁@@l],,Σ₃) |- [σ₂]@l ],,[Γ>Δ> Σ₂ |- [σ₁]@l])     [Γ>Δ> Σ₁,,(Σ₂,,Σ₃) |- [σ₂ ]@l]
+
+| RCut           : ∀ Γ Δ Σ₁ Σ₁₂ Σ₂ Σ₃ l,  Rule ([Γ>Δ> Σ₁ |- Σ₁₂ @l],,[Γ>Δ> (Σ₁₂@@@l),,Σ₂ |- Σ₃@l ]) [Γ>Δ> Σ₁,,Σ₂ |- Σ₃@l]
+| RLeft          : ∀ Γ Δ Σ₁ Σ₂  Σ     l,  Rule  [Γ>Δ> Σ₁ |- Σ₂  @l]                                 [Γ>Δ> (Σ@@@l),,Σ₁ |- Σ,,Σ₂@l]
+| RRight         : ∀ Γ Δ Σ₁ Σ₂  Σ     l,  Rule  [Γ>Δ> Σ₁ |- Σ₂  @l]                                 [Γ>Δ> Σ₁,,(Σ@@@l) |- Σ₂,,Σ@l]
+
+| RVoid    : ∀ Γ Δ l,               Rule [] [Γ > Δ > [] |- [] @l ]
+
+| RAppT   : forall Γ Δ Σ κ σ (τ:HaskType Γ κ) l,      Rule [Γ>Δ> Σ   |- [HaskTAll κ σ]@l]      [Γ>Δ>    Σ     |- [substT σ τ]@l]
 | RAbsT   : ∀ Γ Δ Σ κ σ   l,
-  Rule [(κ::Γ)> (weakCE Δ)    >   mapOptionTree weakLT Σ |- [ HaskTApp (weakF σ) (FreshHaskTyVar _) @@ (weakL l)]]
-       [Γ>Δ            >    Σ     |- [HaskTAll κ σ   @@ l]]
-| RAppCo  : forall Γ Δ Σ κ σ₁ σ₂ σ γ l,   Δ ⊢ᴄᴏ γ  : σ₁∼σ₂ ->
-    Rule [Γ>Δ> Σ |- [σ₁∼∼σ₂:κ ⇒ σ@@l]] [Γ>Δ>    Σ     |- [σ        @@l]]
-| RAbsCo  : ∀ Γ Δ Σ κ σ σ₁ σ₂ l,
-   Γ ⊢ᴛy σ₁:κ ->
-   Γ ⊢ᴛy σ₂:κ ->
-   Rule [Γ > ((σ₁∼∼∼σ₂)::Δ)            > Σ |- [σ @@ l]]
-        [Γ > Δ >                         Σ |- [σ₁∼∼σ₂:κ⇒ σ @@l]]
-| RLetRec        : ∀ Γ Δ Σ₁ τ₁ τ₂, Rule [Γ > Δ > Σ₁,,τ₂ |- τ₁,,τ₂ ] [Γ > Δ > Σ₁ |- τ₁ ]
-| RCase          : forall Γ Δ lev n tc Σ avars tbranches
-  (alts:Tree ??(@ProofCaseBranch n tc Γ lev tbranches avars)),
+  Rule [(κ::Γ)> (weakCE Δ)    >   mapOptionTree weakLT Σ |- [ HaskTApp (weakF σ) (FreshHaskTyVar _) ]@(weakL l)]
+       [Γ>Δ            >    Σ     |- [HaskTAll κ σ   ]@l]
+
+| RAppCo  : forall Γ Δ Σ κ (σ₁ σ₂:HaskType Γ κ) (γ:HaskCoercion Γ Δ (σ₁∼∼∼σ₂)) σ l,
+    Rule [Γ>Δ> Σ |- [σ₁∼∼σ₂ ⇒ σ]@l] [Γ>Δ>    Σ     |- [σ        ]@l]
+| RAbsCo  : forall Γ Δ Σ κ (σ₁ σ₂:HaskType Γ κ) σ l,
+   Rule [Γ > ((σ₁∼∼∼σ₂)::Δ)            > Σ |- [σ ]@l]
+        [Γ > Δ >                         Σ |- [σ₁∼∼σ₂⇒ σ ]@l]
+
+| RLetRec        : forall Γ Δ Σ₁ τ₁ τ₂ lev, Rule [Γ > Δ > Σ₁,,(τ₂@@@lev) |- (τ₂,,[τ₁]) @lev ] [Γ > Δ > Σ₁ |- [τ₁] @lev]
+| RCase          : forall Γ Δ lev tc Σ avars tbranches
+  (alts:Tree ??{ sac : @StrongAltCon tc & @ProofCaseBranch tc Γ Δ lev tbranches avars sac }),
                    Rule
-                       ((mapOptionTree cbri_judg alts),,
-                        [Γ > Δ >                                               Σ |- [ caseType tc avars @@ lev ] ])
-                        [Γ > Δ > (mapOptionTreeAndFlatten cbri_freevars alts),,Σ |- [ tbranches         @@ lev ] ]
+                       ((mapOptionTree (fun x => pcb_judg (projT2 x)) alts),,
+                        [Γ > Δ >                                              Σ |- [ caseType tc avars  ] @lev])
+                        [Γ > Δ > (mapOptionTreeAndFlatten (fun x => pcb_freevars (projT2 x)) alts),,Σ |- [ tbranches ] @ lev]
 .
-Coercion RURule : URule >-> Rule.
 
 
 (* A rule is considered "flat" if it is neither RBrak nor REsc *)
+(* TODO: change this to (if RBrak/REsc -> False) *)
 Inductive Rule_Flat : forall {h}{c}, Rule h c -> Prop :=
-| Flat_RURule           : ∀ Γ Δ  h c r            ,  Rule_Flat (RURule Γ Δ  h c r)
-| Flat_RNote            : ∀ x y z              ,  Rule_Flat (RNote x y z)
+| Flat_RArrange         : ∀ Γ Δ  h c r          a l ,  Rule_Flat (RArrange Γ Δ h c r a l)
+| Flat_RNote            : ∀ Γ Δ Σ τ l n            ,  Rule_Flat (RNote Γ Δ Σ τ l n)
+| Flat_RLit             : ∀ Γ Δ Σ τ               ,  Rule_Flat (RLit Γ Δ Σ τ  )
 | Flat_RVar             : ∀ Γ Δ  σ               l,  Rule_Flat (RVar Γ Δ  σ         l)
-| Flat_RLam             : ∀ Γ Δ  Σ tx te    q    l,  Rule_Flat (RLam Γ Δ  Σ tx te      q l)
-| Flat_RCast            : ∀ Γ Δ  Σ σ τ γ    q    l,  Rule_Flat (RCast Γ Δ  Σ σ τ γ    q l)
+| Flat_RLam             : ∀ Γ Δ  Σ tx te    q    ,  Rule_Flat (RLam Γ Δ  Σ tx te      q )
+| Flat_RCast            : ∀ Γ Δ  Σ σ τ γ    q     ,  Rule_Flat (RCast Γ Δ  Σ σ τ γ    q )
 | Flat_RAbsT            : ∀ Γ   Σ κ σ a    q    ,  Rule_Flat (RAbsT Γ   Σ κ σ a    q )
-| Flat_RAppT            : ∀ Γ Δ  Σ κ σ τ    q    l,  Rule_Flat (RAppT Γ Δ  Σ κ σ τ    q l)
-| Flat_RAppCo           : ∀ Γ Δ  Σ κ σ₁ σ₂ σ γ q l,  Rule_Flat (RAppCo Γ Δ  Σ κ σ₁ σ₂ σ γ  q l)
-| Flat_RAbsCo           : ∀ Γ   Σ κ σ  σ₁ σ₂ q1 q2 q3 x , Rule_Flat (RAbsCo Γ   Σ κ σ  σ₁ σ₂  q1 q2 q3 x )
+| Flat_RAppT            : ∀ Γ Δ  Σ κ σ τ    q    ,  Rule_Flat (RAppT Γ Δ  Σ κ σ τ    q )
+| Flat_RAppCo           : ∀ Γ Δ  Σ σ₁ σ₂ σ γ q l,  Rule_Flat (RAppCo Γ Δ  Σ  σ₁ σ₂ σ γ  q l)
+| Flat_RAbsCo           : ∀ Γ   Σ κ σ  σ₁ σ₂ q1 q2   , Rule_Flat (RAbsCo Γ   Σ κ σ  σ₁ σ₂  q1 q2   )
 | Flat_RApp             : ∀ Γ Δ  Σ tx te   p     l,  Rule_Flat (RApp Γ Δ  Σ tx te   p l)
 | Flat_RLet             : ∀ Γ Δ  Σ σ₁ σ₂   p     l,  Rule_Flat (RLet Γ Δ  Σ σ₁ σ₂   p l)
-| Flat_RBindingGroup    : ∀ q a b c d e ,  Rule_Flat (RBindingGroup q a b c d e)
-| Flat_RCase            : ∀ Σ Γ  T κlen κ θ l x  q, Rule_Flat (RCase Σ Γ T κlen κ θ l x q).
-
-(* given a proof that uses only uniform rules, we can produce a general proof *)
-Definition UND_to_ND Γ Δ h c : ND (@URule Γ Δ) h c -> ND Rule (mapOptionTree UJudg2judg h) (mapOptionTree UJudg2judg c)
-  := @nd_map' _ (@URule Γ Δ ) _ Rule (@UJudg2judg Γ Δ ) (fun h c r => nd_rule (RURule _ _ h c r)) h c.
-
+| Flat_RJoin    : ∀ q a b c d e l,  Rule_Flat (RJoin q a b c d e l)
+| Flat_RVoid      : ∀ q a                  l,  Rule_Flat (RVoid q a l)
+| Flat_RCase            : ∀ Σ Γ  T κlen κ θ l x  , Rule_Flat (RCase Σ Γ T κlen κ θ l x)
+| Flat_RLetRec          : ∀ Γ Δ Σ₁ τ₁ τ₂ lev,      Rule_Flat (RLetRec Γ Δ Σ₁ τ₁ τ₂ lev).
+
+Lemma no_rules_with_empty_conclusion : forall c h, @Rule c h -> h=[] -> False.
+  intros.
+  destruct X; try destruct c; try destruct o; simpl in *; try inversion H.
+  Qed.
+
+Lemma no_rules_with_multiple_conclusions : forall c h,
+  Rule c h -> { h1:Tree ??Judg & { h2:Tree ??Judg & h=(h1,,h2) }} -> False.
+  intros.
+  destruct X; try destruct c; try destruct o; simpl in *; try inversion H;
+    try apply no_urules_with_empty_conclusion in u; try apply u.
+    destruct X0; destruct s; inversion e.
+    auto.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    destruct X0; destruct s; inversion e.
+    Qed.
+
+Lemma systemfc_all_rules_one_conclusion : forall h c1 c2 (r:Rule h (c1,,c2)), False.
+  intros.
+  eapply no_rules_with_multiple_conclusions.
+  apply r.
+  exists c1.
+  exists c2.
+  auto.
+  Qed.