diff --git a/theories/BundledAlgorithmicTyping.v b/theories/BundledAlgorithmicTyping.v
index d5a8093..8321353 100644
--- a/theories/BundledAlgorithmicTyping.v
+++ b/theories/BundledAlgorithmicTyping.v
@@ -691,7 +691,10 @@ Section BundledConv.
       pose proof hp as []%boundary%sig_ty_inv.
       edestruct ihsnd as []; tea.
       1: now econstructor.
-      2: split; [eauto|now econstructor].
+      2:{ split; [eauto|].
+          eapply TermTrans; [|now constructor].
+          eapply TermTrans; [eapply TermSym; now constructor|].
+          constructor; tea; now apply TypeRefl. }
       eapply wfTermConv; [now econstructor|].
       eapply typing_subst1; [now symmetry|].
       now eapply TypeRefl.
diff --git a/theories/DeclarativeInstance.v b/theories/DeclarativeInstance.v
index 5e19279..668dca2 100644
--- a/theories/DeclarativeInstance.v
+++ b/theories/DeclarativeInstance.v
@@ -227,11 +227,16 @@ Section TypingWk.
     - intros * ????? ih ** ; do 2 rewrite <- wk_sig.
       constructor; eauto.
       eapply ih; constructor; tea; constructor; eauto.
-    - intros * ??? ihB **. rewrite <- wk_sig.
+    - intros * ? ihA₀ ? ihA ? ihA' ? ihB ? ihB' ? iha ? ihb Δ ρ **.
+      rewrite <- wk_sig, <- !wk_pair.
+      assert [|-[de] Δ,, A⟨ρ⟩] by now constructor.
       constructor; eauto.
-      1: eapply ihB; constructor; eauto.
-      1,2: rewrite wk_sig; eauto.
-      rewrite wk_fst, <- subst_ren_wk_up; eauto.
+      * now apply ihB.
+      * now apply ihB'.
+      * rewrite <- subst_ren_wk_up; now apply ihb.
+    - intros * ? ihp Δ ρ **.
+      rewrite <- wk_sig, <- wk_pair.
+      constructor; rewrite wk_sig; eauto.
     - intros * ? ih **. econstructor; now eapply ih.
     - intros * ??? ihB ** ; rewrite <- wk_fst; rewrite <- wk_pair; constructor; eauto.
       1: eapply ihB; constructor; eauto.
@@ -531,7 +536,10 @@ Module DeclarativeTypingProperties.
   - now do 2 econstructor.
   - now do 2 econstructor.
   - now econstructor.
-  - intros. econstructor; tea.
+  - intros.
+    eapply TermTrans; [|now constructor].
+    eapply TermTrans; [eapply TermSym; now constructor|].
+    constructor; tea; now apply TypeRefl.
   - now do 2 econstructor.
   - now econstructor.
   - now econstructor.
diff --git a/theories/DeclarativeTyping.v b/theories/DeclarativeTyping.v
index 1bb5091..a8f9309 100644
--- a/theories/DeclarativeTyping.v
+++ b/theories/DeclarativeTyping.v
@@ -217,14 +217,18 @@ Section Definitions.
           [ Γ |- A ≅ A' : U ] ->
           [ Γ ,, A |- B ≅ B' : U ] ->
           [ Γ |- tSig A B ≅ tSig A' B' : U ]
-      | TermPairEta {Γ} {A B p q} :
+      | TermPairCong {Γ A A' A'' B B' B'' a a' b b'} :
           [Γ |- A] ->
-          [Γ ,, A |- B] ->
+          [Γ |- A ≅ A'] ->
+          [Γ |- A ≅ A''] ->
+          [Γ,, A |- B ≅ B'] ->
+          [Γ,, A |- B ≅ B''] ->
+          [Γ |- a ≅ a' : A] ->
+          [Γ |- b ≅ b' : B[a..]] ->
+          [Γ |- tPair A' B' a b ≅ tPair A'' B'' a' b' : tSig A B]
+      | TermPairEta {Γ} {A B p} :
           [Γ |- p : tSig A B] ->
-          [Γ |- q : tSig A B] ->
-          [Γ |- tFst p ≅ tFst q : A] ->
-          [Γ |- tSnd p ≅ tSnd q : B[(tFst p)..]] ->
-          [Γ |- p ≅ q : tSig A B]
+          [Γ |- tPair A B (tFst p) (tSnd p) ≅ p : tSig A B]
       | TermFstCong {Γ A B p p'} :
         [Γ |- p ≅ p' : tSig A B] ->
         [Γ |- tFst p ≅ tFst p' : A]
diff --git a/theories/Fundamental.v b/theories/Fundamental.v
index b344c07..73719d1 100644
--- a/theories/Fundamental.v
+++ b/theories/Fundamental.v
@@ -768,20 +768,167 @@ Section Fundamental.
     Unshelve. all: solve [ eapply UValid | now eapply univValid | irrValid].
   Qed.
 
-  Lemma FundTmEqSigEta : forall (Γ : context) (A B p q : term),
+  Lemma FundTmEqPairCong : forall (Γ : context) (A A' A'' B B' B'' a a' b b' : term),
     FundTy Γ A ->
-    FundTy (Γ,, A) B ->
-    FundTm Γ (tSig A B) p ->
-    FundTm Γ (tSig A B) q ->
-    FundTmEq Γ A (tFst p) (tFst q) ->
-    FundTmEq Γ B[(tFst p)..] (tSnd p) (tSnd q) -> FundTmEq Γ (tSig A B) p q.
+    FundTyEq Γ A A' ->
+    FundTyEq Γ A A'' ->
+    FundTyEq (Γ,, A) B B' ->
+    FundTyEq (Γ,, A) B B'' ->
+    FundTmEq Γ A a a' ->
+    FundTmEq Γ B[a..] b b' -> FundTmEq Γ (tSig A B) (tPair A' B' a b) (tPair A'' B'' a' b').
   Proof.
-    intros * [] [] [] [] [] []; unshelve econstructor.
-    5: eapply sigEtaValid; tea; irrValid.
-    all: irrValid.
-    Unshelve. all: irrValid.
+    intros * [VΓ VA] [] [] [] [] [] [].
+    assert (VΣ : [Γ ||-v< one > tSig A B | VΓ]).
+    { unshelve eapply SigValid; irrValid. }
+    assert (VA' : [Γ ||-v< one > A' | VΓ]) by irrValid.
+    assert (VA'' : [Γ ||-v< one > A'' | VΓ]) by irrValid.
+    assert ([Γ ||-v< one > a : A' | VΓ | VA']).
+    { eapply conv; [|irrValid]; irrValid. Unshelve. tea. }
+    assert ([Γ ||-v< one > a : A'' | VΓ | VA'']).
+    { eapply conv; [irrValid|]; irrValid. Unshelve. tea. }
+    assert ([Γ ||-v< one > a' : A'' | VΓ | VA'']).
+    { eapply conv; [irrValid|]; irrValid. Unshelve. tea. }
+    assert (VΓA' : VAdequate (ta := ta) (Γ,, A') VR) by now eapply validSnoc.
+    assert (VΓA'' : VAdequate (ta := ta) (Γ,, A'') VR) by now eapply validSnoc.
+    assert (VA'B : [Γ,, A' ||-v< one > B | VΓA']).
+    { eapply irrelevanceTy, irrelevanceLift; irrValid.
+      Unshelve. all: irrValid. }
+    assert (VA''B : [Γ,, A'' ||-v< one > B | VΓA'']).
+    { eapply irrelevanceTy, irrelevanceLift; irrValid.
+      Unshelve. all: irrValid. }
+    assert (VA'B' : [Γ,, A' ||-v< one > B' | VΓA']).
+    { eapply irrelevanceTy, irrelevanceLift; try irrValid.
+      Unshelve. all: irrValid. }
+    assert (VA''B' : [Γ,, A'' ||-v< one > B' | VΓA'']).
+    { eapply irrelevanceTy, irrelevanceLift; try irrValid.
+      Unshelve. all: irrValid. }
+    assert (VA''B'' : [Γ,, A'' ||-v< one > B'' | VΓA'']).
+    { eapply irrelevanceTy, irrelevanceLift; try irrValid.
+      Unshelve. all: irrValid. }
+    assert (VBa : [Γ ||-v< one > B[a..] | VΓ]).
+    { irrValid. }
+    assert (VB'a : [Γ ||-v< one > B'[a..] | VΓ]).
+    { eapply substS; irrValid. Unshelve. all: irrValid. }
+    assert (VB''a : [Γ ||-v< one > B''[a..] | VΓ]).
+    { eapply substS; irrValid. Unshelve. all: irrValid. }
+    assert (VB''a' : [Γ ||-v< one > B''[a'..] | VΓ]).
+    { eapply substS; irrValid. Unshelve. all: irrValid. }
+    assert [Γ ||-v< one > B[a..] ≅ B'[a..] | VΓ | VBa].
+    { eapply irrelevanceTyEq, substSEq; try irrValid.
+      apply reflValidTm. irrValid. Unshelve. all: irrValid. }
+    assert [Γ ||-v< one > B[a..] ≅ B''[a'..] | VΓ | VBa].
+    { eapply irrelevanceTyEq, substSEq; [..|irrValid|irrValid].
+      all: irrValid. Unshelve. all: irrValid. }
+    assert (VΣA'B' : [Γ ||-v< one > tSig A' B' | VΓ]).
+    { unshelve eapply SigValid; try irrValid. }
+    assert (VΣA''B'' : [Γ ||-v< one > tSig A'' B'' | VΓ]).
+    { unshelve eapply SigValid; try irrValid. }
+    assert ([Γ ||-v< one > tSig A B ≅ tSig A' B' | VΓ | VΣ]).
+    { unshelve eapply irrelevanceTyEq, SigCong; try irrValid. }
+    assert ([Γ ||-v< one > tSig A B ≅ tSig A'' B'' | VΓ | VΣ]).
+    { unshelve eapply irrelevanceTyEq, SigCong; try irrValid. }
+    assert [Γ ||-v< one > tPair A' B' a b : tSig A B | _ | VΣ ].
+    { eapply conv; [|unshelve eapply pairValid]; try irrValid.
+      - unshelve eapply symValidTyEq; irrValid.
+      - eapply conv; irrValid. Unshelve. all: irrValid. }
+    assert [Γ ||-v< one > tPair A'' B'' a' b' : tSig A B | _ | VΣ ].
+    { eapply conv; [|unshelve eapply pairValid]; try irrValid.
+      - unshelve eapply symValidTyEq; irrValid.
+      - eapply conv; irrValid.
+        Unshelve. all: irrValid. }
+    assert [Γ ||-v< one > b : B'[a..] | VΓ | VB'a].
+    { eapply conv; irrValid. Unshelve. all: irrValid. }
+    assert [Γ ||-v< one > b' : B''[a'..] | VΓ | VB''a'].
+    { eapply conv; irrValid. Unshelve. all: irrValid. }
+    assert ([Γ ||-v< one > tFst (tPair A' B' a b) ≅ a : A | VΓ | VA]).
+    { eapply (convEq (A := A')); [eapply symValidTyEq; irrValid|].
+      eapply pairFstValid. Unshelve. all: try irrValid. }
+    assert ([Γ ||-v< one > tFst (tPair A'' B'' a' b') ≅ a' : A | VΓ | VA]).
+    { eapply (convEq (A := A'')); [eapply symValidTyEq; irrValid|].
+      eapply pairFstValid. Unshelve. all: irrValid. }
+    assert ([Γ ||-v< one > tFst (tPair A' B' a b) ≅ tFst (tPair A'' B'' a' b') : A | VΓ | VA]).
+    { eapply transValidTmEq; [irrValid|].
+      eapply transValidTmEq; [irrValid|].
+      eapply symValidTmEq; irrValid. }
+    assert ([Γ ||-v< one > tFst (tPair A' B' a b) : A | VΓ | VA]).
+    { eapply fstValid. Unshelve. all: try irrValid. }
+    assert ([Γ ||-v< one > tFst (tPair A'' B'' a' b') : A | VΓ | VA]).
+    { eapply fstValid. Unshelve. all: try irrValid. }
+    assert (VBfst : [Γ ||-v< one > B[(tFst (tPair A' B' a b))..] | VΓ]).
+    { eapply (substS (F := A)). Unshelve. all: try  irrValid. }
+    assert (VB'fst : [Γ ||-v< one > B'[(tFst (tPair A' B' a b))..] | VΓ]).
+    { eapply (substS (F := A)). Unshelve. all: try  irrValid. }
+    assert (VB''fst' : [Γ ||-v< one > B''[(tFst (tPair A'' B'' a' b'))..] | VΓ]).
+    { eapply (substS (F := A)). Unshelve. all: try irrValid. }
+    assert ([Γ ||-v< one > B[(tFst (tPair A' B' a b))..] ≅ B[a..] | VΓ | VBfst]).
+    { eapply irrelevanceTyEq, substSEq; [..|irrValid|irrValid].
+      Unshelve. all: try irrValid. eapply reflValidTy. }
+    assert ([Γ ||-v< one > B'[(tFst (tPair A' B' a b))..] ≅ B[a..] | VΓ | VB'fst]).
+    { eapply irrelevanceTyEq, substSEq; [..|irrValid|irrValid].
+      Unshelve. all: try irrValid.
+      eapply symValidTyEq; irrValid. Unshelve. all: try irrValid. }
+    assert ([Γ ||-v< one > B''[(tFst (tPair A'' B'' a' b'))..] ≅ B[a'..] | VΓ | VB''fst']).
+    { eapply irrelevanceTyEq, substSEq; [..|irrValid|].
+      Unshelve. all: try irrValid.
+      eapply symValidTyEq; irrValid. Unshelve. all: try irrValid. }
+    assert ([Γ ||-v< one > B''[(tFst (tPair A'' B'' a' b'))..] ≅ B[a..] | VΓ | VB''fst']).
+    { eapply irrelevanceTyEq, substSEq; [..|irrValid|].
+      Unshelve. all: try irrValid.
+      eapply symValidTyEq; irrValid. Unshelve. all: try irrValid.
+      eapply transValidTmEq; [irrValid|].
+      eapply symValidTmEq; irrValid.
+    }
+    assert ([Γ ||-v< one > tSnd (tPair A' B' a b) ≅ b : B[(tFst (tPair A' B' a b))..] | VΓ | VBfst]).
+    { eapply (convEq (A := B'[(tFst (tPair A' B' a b))..])).
+      shelve. eapply pairSndValid.
+      Unshelve. all: try irrValid.
+      eapply irrelevanceTyEq, substSEq; [..|irrValid|apply reflValidTm; irrValid].
+      all: try irrValid.
+      - unshelve apply reflValidTy.
+      - unshelve eapply symValidTyEq; irrValid. }
+    assert ([Γ ||-v< one > tSnd (tPair A'' B'' a' b') ≅ b' : B[a..] | VΓ | VBa]).
+    { eapply (convEq (A := B''[(tFst (tPair A'' B'' a' b'))..])).
+      shelve. eapply pairSndValid.
+      Unshelve. all: try irrValid. }
+    unshelve econstructor. 1-4: irrValid.
+    eapply irrelevanceTmEq, sigEtaValid; try irrValid.
+    eapply transValidTmEq; [irrValid|].
+    eapply transValidTmEq.
+    - eapply convEq; [|irrValid].
+      eapply symValidTyEq; try irrValid.
+    - eapply symValidTmEq; try irrValid.
+      eapply convEq; [|irrValid].
+      eapply symValidTyEq; try irrValid.
+  Unshelve. all: try irrValid.
   Qed.
 
+  Lemma FundTmEqSigEta : forall (Γ : context) (A B p : term),
+    FundTm Γ (tSig A B) p -> FundTmEq Γ (tSig A B) (tPair A B (tFst p) (tSnd p)) p.
+  Proof.
+  intros * [VΓ VΣ Vp].
+  assert (VA := domSigValid _ VΣ).
+  assert (VB := codSigValid _ VΣ).
+  assert (Vfst : [Γ ||-v< one > tFst p : A | _ | VA]).
+  { unshelve eapply irrelevanceTm, fstValid; try irrValid. }
+  assert (VBfst : [Γ ||-v< one > B[(tFst p)..] | VΓ]).
+  { unshelve eapply substS; try irrValid. }
+  assert (Vsnd : [Γ ||-v< one > tSnd p : B[(tFst p)..] | _ | VBfst]).
+  { unshelve eapply irrelevanceTm, sndValid.
+    5: irrValid. all: irrValid. }
+  assert (Vηp : [Γ ||-v< one > tPair A B (tFst p) (tSnd p) : tSig A B | VΓ | VΣ]).
+  { unshelve eapply irrelevanceTm, pairValid; try irrValid. }
+  unshelve econstructor; try irrValid.
+  eapply irrelevanceTmEq, sigEtaValid; try irrValid.
+  - eapply transValidTmEq; [eapply pairFstValid|eapply reflValidTm].
+    Unshelve. all: try irrValid.
+  - eapply transValidTmEq; [unshelve eapply irrelevanceTmEq, pairSndValid|unshelve eapply reflValidTm]; try irrValid.
+    unshelve eapply conv; try irrValid.
+    eapply irrelevanceTyEq, substSEq; try irrValid.
+    1,2: unshelve apply reflValidTy.
+    { unshelve eapply fstValid; try irrValid. }
+    { unshelve eapply symValidTmEq, pairFstValid; try irrValid. }
+    Unshelve. all: try irrValid.
+  Qed.
 
   Lemma FundTmEqFstCong : forall (Γ : context) (A B p p' : term),
     FundTmEq Γ (tSig A B) p p' -> FundTmEq Γ A (tFst p) (tFst p').
@@ -1055,6 +1202,7 @@ Lemma Fundamental : (forall Γ : context, [ |-[ de ] Γ ] -> FundCon (ta := ta)
   + intros; now apply FundTmEqNatElimSucc.
   + intros; now apply FundTmEqEmptyElimCong.
   + intros; now apply FundTmEqSigCong.
+  + intros; now apply FundTmEqPairCong.
   + intros; now apply FundTmEqSigEta.
   + intros; now eapply FundTmEqFstCong.
   + intros; now apply FundTmEqFstBeta.
diff --git a/theories/Substitution/Introductions/Sigma.v b/theories/Substitution/Introductions/Sigma.v
index b974ca1..cf5c624 100644
--- a/theories/Substitution/Introductions/Sigma.v
+++ b/theories/Substitution/Introductions/Sigma.v
@@ -977,8 +977,6 @@ Section PairRed.
     + irrelevance0. 1: now rewrite <- subst_fst, <- singleSubstComm'. tea.
   Qed. 
 
-
-  
 End PairRed.