39 lines
1.4 KiB
Text
39 lines
1.4 KiB
Text
/- the construction of the Gysin sequence using the Serre spectral sequence -/
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-- author: Floris van Doorn
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import .serre
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open eq pointed is_trunc is_conn is_equiv equiv sphere fiber chain_complex left_module spectrum nat
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prod nat int algebra
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namespace cohomology
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definition gysin_sequence' {E B : Type*} (n : ℕ) (HB : is_conn 1 B) (f : E →* B)
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(e : pfiber f ≃* sphere (n+1)) (A : AbGroup) : chain_complex +3ℤ :=
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let c := serre_spectral_sequence_map_of_is_conn pt f (EM_spectrum A) 0 (is_strunc_EM_spectrum A) HB
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in
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left_module.LES_of_SESs _ _ _ (λm, convergent_spectral_sequence.d c n (m, n))
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begin
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intro m,
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fapply short_exact_mod_isomorphism,
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rotate 3,
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{ fapply short_exact_mod_of_is_contr_submodules
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(spectral_sequence.convergence_0 c (n + m) (λm, neg_zero)),
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{ exact zero_lt_succ n },
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{ intro k Hk0 Hkn, apply spectral_sequence.is_contr_E,
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apply is_contr_ordinary_cohomology,
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refine is_contr_equiv_closed_rev _
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(unreduced_ordinary_cohomology_sphere_of_neq_nat A Hkn Hk0),
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apply group.equiv_of_isomorphism, apply unreduced_ordinary_cohomology_isomorphism,
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exact e⁻¹ᵉ* }},
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end
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-- (λm, short_exact_mod_isomorphism
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-- _
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-- isomorphism.rfl
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-- _
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-- (short_exact_mod_of_is_contr_submodules
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-- (convergent_spectral_sequence.HDinf X _)
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-- (zero_lt_succ n)
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-- _))
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end cohomology
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