diff --git a/algebra/module_chain_complex.hlean b/algebra/module_chain_complex.hlean
index 6c5f03e..626f915 100644
--- a/algebra/module_chain_complex.hlean
+++ b/algebra/module_chain_complex.hlean
@@ -14,18 +14,18 @@ structure module_chain_complex (R : Ring) (N : succ_str) : Type :=
 (is_chain_complex :
   Π (n : N) (x : mod (S (S n))), hom n (hom (S n) x) = 0)
 
-namespace module_chain_complex
+namespace left_module
   variables {R : Ring} {N : succ_str}
 
-  definition mcc_mod [unfold 2] [coercion] (C : module_chain_complex R N) (n : N) :
+  definition mcc_mod [unfold 3] [coercion] (C : module_chain_complex R N) (n : N) :
     LeftModule R :=
   module_chain_complex.mod C n
 
-  definition mcc_carr [unfold 2] [coercion] (C : module_chain_complex R N) (n : N) :
+  definition mcc_carr [unfold 3] [coercion] (C : module_chain_complex R N) (n : N) :
     Type :=
   C n
 
-  definition mcc_pcarr [unfold 2] [coercion] (C : module_chain_complex R N) (n : N) :
+  definition mcc_pcarr [unfold 3] [coercion] (C : module_chain_complex R N) (n : N) :
     Set* :=
   mcc_mod C n
 
@@ -46,7 +46,11 @@ namespace module_chain_complex
   -- maybe we don't even need this?
   definition is_exact_at_m (C : module_chain_complex R N) (n : N) : Type :=
   is_exact_at C n
-end module_chain_complex
+
+  definition is_exact_m (C : module_chain_complex R N) : Type :=
+  ∀n, is_exact_at_m C n
+
+end left_module
 
 namespace left_module
   variable  {R : Ring}
diff --git a/algebra/spectral_sequence.hlean b/algebra/spectral_sequence.hlean
index 637487d..d8cf035 100644
--- a/algebra/spectral_sequence.hlean
+++ b/algebra/spectral_sequence.hlean
@@ -159,6 +159,10 @@ namespace spectral_sequence
   variable {c}
   variable (nc : is_normal c)
   include nc
+
+  definition deg_d_normal_pr1 (r : ℕ) : (deg_d c r).1 = r+2    := ap pr1 (normal3 nc r)
+  definition deg_d_normal_pr2 (r : ℕ) : (deg_d c r).2 = -(r+1) := ap pr2 (normal3 nc r)
+
   definition stable_range {n s : ℤ} {r : ℕ} (H1 : n < r + 2) (H2 : s < r + 1) :
     Einf c (n, s) ≃lm E c r (n, s) :=
   begin
diff --git a/algebra/submodule.hlean b/algebra/submodule.hlean
index 9c95d4d..a325b35 100644
--- a/algebra/submodule.hlean
+++ b/algebra/submodule.hlean
@@ -1,10 +1,10 @@
 /- submodules and quotient modules -/
 
 -- Authors: Floris van Doorn, Jeremy Avigad
-import .left_module .quotient_group
+import .left_module .quotient_group .module_chain_complex
 
 open algebra eq group sigma sigma.ops is_trunc function trunc equiv is_equiv property
-
+universe variable u
 namespace left_module
 /- submodules -/
 variables {R : Ring} {M M₁ M₁' M₂ M₂' M₃ M₃' : LeftModule R} {m m₁ m₂ : M}
@@ -484,19 +484,17 @@ quotient_module_isomorphism_quotient_module
   begin intro m, reflexivity end
 
 open chain_complex fin nat
-definition LES_of_SESs.{u} {N : succ_str} (A B C : N → LeftModule.{_ u} R) (φ : Πn, A n →lm B n)
+definition LES_of_SESs {N : succ_str} (A B C : N → LeftModule.{_ u} R) (φ : Πn, A n →lm B n)
   (ses : Πn : N, short_exact_mod (cokernel_module (φ (succ_str.S n))) (C n) (kernel_module (φ n))) :
-  chain_complex.{_ u} (stratified N 2) :=
+  module_chain_complex.{_ _ u} R (stratified N 2) :=
 begin
-  fapply chain_complex.mk,
-  { intro x, apply @pSet_of_LeftModule R,
-    induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
+  fapply module_chain_complex.mk,
+  { intro x, induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
     { /-k≥3-/ exfalso, apply lt_le_antisymm H, apply le_add_left},
     { /-k=0-/ exact B n },
     { /-k=1-/ exact A n },
     { /-k=2-/ exact C n }},
-  { intro x, apply @pmap_of_homomorphism R,
-    induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
+  { intro x, induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
     { /-k≥3-/ exfalso, apply lt_le_antisymm H, apply le_add_left},
     { /-k=0-/ exact φ n },
     { /-k=1-/ exact submodule_incl _ ∘lm short_exact_mod.g (ses n) },
@@ -504,14 +502,32 @@ begin
   { intros x m, induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
     { exfalso, apply lt_le_antisymm H, apply le_add_left},
     { exact (short_exact_mod.g (ses n) m).2 },
-    { exact ap pr1 (is_short_exact.im_in_ker (short_exact_mod.h (ses n)) (quotient_map _ m)) },
-    { exact ap (short_exact_mod.f (ses n)) (quotient_map_eq_zero _ _ (image.mk m idp)) ⬝
-            to_respect_zero (short_exact_mod.f (ses n)) }}
+    { note h := is_short_exact.im_in_ker (short_exact_mod.h (ses n)) (quotient_map _ m),
+      exact ap pr1 h },
+    { refine _ ⬝ to_respect_zero (short_exact_mod.f (ses n)),
+      rexact ap (short_exact_mod.f (ses n)) (quotient_map_eq_zero _ _ (image.mk m idp)) }}
 end
 
-definition is_exact_LES_of_SESs.{u} {N : succ_str} (A B C : N → LeftModule.{_ u} R) (φ : Πn, A n →lm B n)
+open prod
+definition LES_of_SESs_zero {N : succ_str} {A B C : N → LeftModule.{_ u} R} (φ : Πn, A n →lm B n)
+  (ses : Πn : N, short_exact_mod (cokernel_module (φ (succ_str.S n))) (C n) (kernel_module (φ n)))
+  (n : N) : LES_of_SESs A B C φ ses (n, 0) ≃lm B n :=
+by reflexivity
+
+definition LES_of_SESs_one {N : succ_str} {A B C : N → LeftModule.{_ u} R} (φ : Πn, A n →lm B n)
+  (ses : Πn : N, short_exact_mod (cokernel_module (φ (succ_str.S n))) (C n) (kernel_module (φ n)))
+  (n : N) : LES_of_SESs A B C φ ses (n, 1) ≃lm A n :=
+by reflexivity
+
+definition LES_of_SESs_two {N : succ_str} {A B C : N → LeftModule.{_ u} R} (φ : Πn, A n →lm B n)
+  (ses : Πn : N, short_exact_mod (cokernel_module (φ (succ_str.S n))) (C n) (kernel_module (φ n)))
+  (n : N) : LES_of_SESs A B C φ ses (n, 2) ≃lm C n :=
+by reflexivity
+
+definition is_exact_LES_of_SESs {N : succ_str} {A B C : N → LeftModule.{_ u} R}
+  (φ : Πn, A n →lm B n)
   (ses : Πn : N, short_exact_mod (cokernel_module (φ (succ_str.S n))) (C n) (kernel_module (φ n))) :
-  is_exact (LES_of_SESs A B C φ ses) :=
+  is_exact_m (LES_of_SESs A B C φ ses) :=
 begin
   intros x m p, induction x with n k, induction k with k H, do 3 (cases k with k; rotate 1),
   { exfalso, apply lt_le_antisymm H, apply le_add_left},
diff --git a/cohomology/basic.hlean b/cohomology/basic.hlean
index 8ee200f..fcaac45 100644
--- a/cohomology/basic.hlean
+++ b/cohomology/basic.hlean
@@ -395,14 +395,14 @@ definition unreduced_ordinary_cohomology_pbool_nonzero (G : AbGroup) (n : ℤ) (
 is_contr_equiv_closed_rev (equiv_of_isomorphism (unreduced_ordinary_cohomology_nonzero pbool G n H))
                           (ordinary_cohomology_dimension G n H)
 
-definition unreduced_ordinary_cohomology_sphere_zero (G : AbGroup) (n : ℕ) (H : n ≠ 0) :
+definition unreduced_ordinary_cohomology_sphere_zero (G : AbGroup.{u}) (n : ℕ) (H : n ≠ 0) :
   uoH^0[sphere n, G] ≃g G :=
 unreduced_ordinary_cohomology_zero (sphere n) G ⬝g
-product_trivial_left _ _ (ordinary_cohomology_sphere_of_neq _ (λh, H h⁻¹))
+product_trivial_left _ _ (ordinary_cohomology_sphere_of_neq _ (λh, H (of_nat.inj h⁻¹)))
 
 definition unreduced_ordinary_cohomology_sphere (G : AbGroup) (n : ℕ) (H : n ≠ 0) :
   uoH^n[sphere n, G] ≃g G :=
-unreduced_ordinary_cohomology_nonzero (sphere n) G n H ⬝g
+unreduced_ordinary_cohomology_nonzero (sphere n) G n (λh, H (of_nat.inj h)) ⬝g
 ordinary_cohomology_sphere G n
 
 definition unreduced_ordinary_cohomology_sphere_of_neq (G : AbGroup) {n : ℤ} {k : ℕ} (p : n ≠ k)
@@ -415,6 +415,11 @@ definition unreduced_ordinary_cohomology_sphere_of_neq_nat (G : AbGroup) {n k :
   (q : n ≠ 0) : is_contr (uoH^n[sphere k, G]) :=
 unreduced_ordinary_cohomology_sphere_of_neq G (λh, p (of_nat.inj h)) (λh, q (of_nat.inj h))
 
+definition unreduced_ordinary_cohomology_sphere_of_gt (G : AbGroup) {n k : ℕ} (p : n > k) :
+  is_contr (uoH^n[sphere k, G]) :=
+unreduced_ordinary_cohomology_sphere_of_neq_nat
+  G (ne_of_gt p) (ne_of_gt (lt_of_le_of_lt (zero_le k) p))
+
 theorem is_contr_cohomology_of_is_contr_spectrum (n : ℤ) (X : Type*) (Y : spectrum)
   (H : is_contr (Y n)) : is_contr (H^n[X, Y]) :=
 begin
diff --git a/cohomology/gysin.hlean b/cohomology/gysin.hlean
index eed4574..f71b936 100644
--- a/cohomology/gysin.hlean
+++ b/cohomology/gysin.hlean
@@ -4,9 +4,10 @@
 import .serre
 
 open eq pointed is_trunc is_conn is_equiv equiv sphere fiber chain_complex left_module spectrum nat
-     prod nat int algebra function spectral_sequence
+     prod nat int algebra function spectral_sequence fin group
 
 namespace cohomology
+universe variable u
 /-
   We have maps:
   d_m = d_(m-1,n+1)^n : E_(m-1,n+1)^n → E_(m+n+1,0)^n
@@ -20,8 +21,30 @@ namespace cohomology
   ... E_(m+n,0)^n → D_{m+n}^∞ → E_(m-1,n+1)^n → E_(m+n+1,0)^n → D_{m+n+1}^∞ ...
 -/
 
-definition gysin_sequence' {E B : Type*} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
-  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) : chain_complex -3ℤ :=
+
+definition gysin_trivial_Epage {E B : pType.{u}} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (r : ℕ) (p q : ℤ) (hq : q ≠ 0)
+  (hq' : q ≠ of_nat (n+1)):
+  is_contr (convergent_spectral_sequence.E (serre_spectral_sequence_map_of_is_conn pt f
+    (EM_spectrum A) 0 (is_strunc_EM_spectrum A) HB) r (p, q)) :=
+begin
+  intros, apply is_contr_E, apply is_contr_ordinary_cohomology, esimp,
+  refine is_contr_equiv_closed_rev _ (unreduced_ordinary_cohomology_sphere_of_neq A hq' hq),
+  apply group.equiv_of_isomorphism, apply unreduced_ordinary_cohomology_isomorphism, exact e⁻¹ᵉ*
+end
+
+definition gysin_trivial_Epage2 {E B : pType.{u}} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (r : ℕ) (p q : ℤ) (hq : q > n+1) :
+  is_contr (convergent_spectral_sequence.E (serre_spectral_sequence_map_of_is_conn pt f
+    (EM_spectrum A) 0 (is_strunc_EM_spectrum A) HB) r (p, q)) :=
+begin
+  intros, apply gysin_trivial_Epage HB f e A r p q,
+  { intro h, subst h, apply not_lt_zero (n+1), exact lt_of_of_nat_lt_of_nat hq },
+  { intro h, subst h, exact lt.irrefl _ hq }
+end
+
+definition gysin_sequence' {E B : pType.{u}} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) : module_chain_complex rℤ -3ℤ :=
 let c := serre_spectral_sequence_map_of_is_conn pt f (EM_spectrum A) 0
   (is_strunc_EM_spectrum A) HB in
 let cn : is_normal c := !is_normal_serre_spectral_sequence_map_of_is_conn in
@@ -36,18 +59,10 @@ begin
 end,
 have trivial_E : Π(r : ℕ) (p q : ℤ) (hq : q ≠ 0) (hq' : q ≠ of_nat (n+1)),
   is_contr (convergent_spectral_sequence.E c r (p, q)),
-begin
-  intros, apply is_contr_E, apply is_contr_ordinary_cohomology, esimp,
-  refine is_contr_equiv_closed_rev _ (unreduced_ordinary_cohomology_sphere_of_neq A hq' hq),
-  apply group.equiv_of_isomorphism, apply unreduced_ordinary_cohomology_isomorphism, exact e⁻¹ᵉ*
-end,
+from gysin_trivial_Epage HB f e A,
 have trivial_E' : Π(r : ℕ) (p q : ℤ) (hq : q > n+1),
   is_contr (convergent_spectral_sequence.E c r (p, q)),
-begin
-  intros, apply trivial_E r p q,
-  { intro h, subst h, apply not_lt_zero (n+1), exact lt_of_of_nat_lt_of_nat hq },
-  { intro h, subst h, exact lt.irrefl _ hq }
-end,
+from gysin_trivial_Epage2 HB f e A,
 left_module.LES_of_SESs _ _ _ (λm, convergent_spectral_sequence.d c n (m - 1, n + 1))
   begin
     intro m,
@@ -96,13 +111,68 @@ left_module.LES_of_SESs _ _ _ (λm, convergent_spectral_sequence.d c n (m - 1, n
         refine ap (λx, x + _) !add.right_inv ⬝ !zero_add }}
   end
 
--- open fin
--- definition gysin_sequence'_zero_equiv {E B : Type*} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
---   (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (m : ℤ) :
---   gysin_sequence' HB f e A (m, 0) ≃ _ :=
--- _
-
+-- set_option pp.universes true
+-- print unreduced_ordinary_cohomology_sphere_zero
+-- print unreduced_ordinary_cohomology_zero
+-- print ordinary_cohomology_sphere_of_neq
+-- set_option formatter.hide_full_terms false
+definition gysin_sequence'_zero {E B : Type*} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (m : ℤ) :
+  gysin_sequence' HB f e A (m, 0) ≃lm LeftModule_int_of_AbGroup (uoH^m+n+1[B, A]) :=
+let c := serre_spectral_sequence_map_of_is_conn pt f (EM_spectrum A) 0
+  (is_strunc_EM_spectrum A) HB in
+let cn : is_normal c := !is_normal_serre_spectral_sequence_map_of_is_conn in
+begin
+  refine LES_of_SESs_zero _ _ m ⬝lm _,
+  transitivity convergent_spectral_sequence.E c n (m+n+1, 0),
+  exact isomorphism_of_eq (ap (convergent_spectral_sequence.E c n)
+   (deg_d_normal_eq cn _ _ ⬝ prod_eq (add.comm4 m (- 1) n 2) (add.right_inv (n+1)))),
+  refine E_isomorphism0 _ _ _ ⬝lm
+    lm_iso_int.mk (unreduced_ordinary_cohomology_isomorphism_right _ _ _),
+  { intros r hr, apply is_contr_ordinary_cohomology,
+    refine is_contr_equiv_closed_rev
+      (equiv_of_isomorphism (cohomology_change_int _ _ _ ⬝g uoH^≃r+1[e⁻¹ᵉ*, A]))
+      (unreduced_ordinary_cohomology_sphere_of_neq_nat A _ _),
+    { exact !zero_sub ⬝ ap neg (deg_d_normal_pr2 cn r) ⬝ !neg_neg },
+    { apply ne_of_lt, apply add_lt_add_right, exact hr },
+    { apply succ_ne_zero }},
+  { intros r hr, apply is_contr_ordinary_cohomology,
+    refine is_contr_equiv_closed_rev
+      (equiv_of_isomorphism (cohomology_change_int _ _ (!zero_add ⬝ deg_d_normal_pr2 cn r)))
+      (is_contr_ordinary_cohomology_of_neg _ _ _),
+    { rewrite [-neg_zero], apply neg_lt_neg, apply of_nat_lt_of_nat_of_lt, apply zero_lt_succ }},
+  { exact uoH^≃ 0[e⁻¹ᵉ*, A] ⬝g unreduced_ordinary_cohomology_sphere_zero _ _ (succ_ne_zero n) }
+end
 
+definition gysin_sequence'_one {E B : Type*} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (m : ℤ) :
+  gysin_sequence' HB f e A (m, 1) ≃lm LeftModule_int_of_AbGroup (uoH^m - 1[B, A]) :=
+let c := serre_spectral_sequence_map_of_is_conn pt f (EM_spectrum A) 0
+  (is_strunc_EM_spectrum A) HB in
+let cn : is_normal c := !is_normal_serre_spectral_sequence_map_of_is_conn in
+begin
+  refine LES_of_SESs_one _ _ m ⬝lm _,
+  refine E_isomorphism0 _ _ _ ⬝lm
+    lm_iso_int.mk (unreduced_ordinary_cohomology_isomorphism_right _ _ _),
+  { intros r hr, apply is_contr_ordinary_cohomology,
+    refine is_contr_equiv_closed_rev
+      (equiv_of_isomorphism uoH^≃_[e⁻¹ᵉ*, A])
+      (unreduced_ordinary_cohomology_sphere_of_gt _ _),
+    { apply lt_add_of_pos_right, apply zero_lt_succ }},
+  { intros r hr, apply is_contr_ordinary_cohomology,
+    refine is_contr_equiv_closed_rev
+      (equiv_of_isomorphism (cohomology_change_int _ _ _ ⬝g uoH^≃n-r[e⁻¹ᵉ*, A]))
+      (unreduced_ordinary_cohomology_sphere_of_neq_nat A _ _),
+    { refine ap (add _) (deg_d_normal_pr2 cn r) ⬝ add_sub_comm n 1 r 1 ⬝ !add_zero ⬝ _,
+      symmetry, apply of_nat_sub, exact le_of_lt hr },
+    { apply ne_of_lt, exact lt_of_le_of_lt (nat.sub_le n r) (lt.base n) },
+    { apply ne_of_gt, exact nat.sub_pos_of_lt hr }},
+  { refine uoH^≃n+1[e⁻¹ᵉ*, A] ⬝g unreduced_ordinary_cohomology_sphere _ _ (succ_ne_zero n) }
+end
 
+definition gysin_sequence'_two {E B : Type*} {n : ℕ} (HB : is_conn 1 B) (f : E →* B)
+  (e : pfiber f ≃* sphere (n+1)) (A : AbGroup) (m : ℤ) :
+  gysin_sequence' HB f e A (m, 2) ≃lm LeftModule_int_of_AbGroup (uoH^n+m[E, A]) :=
+LES_of_SESs_two _ _ m
 
 end cohomology