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2. MARCO TEÓRICO

2.5. Fundamentación histórica

2.5.2. El deporte, su historia y la aparición de la mujer

ofcBF[m,aF,G]under projection to the module HIw1 (Q(μm)⊗Qp,,F−−DVV2(F⊗G)∗)is zero.

Proof By taking the Vi sufficiently small, we may assume that F−−DV1×V2(FG)∗

is actually isomorphic to RA(α−1), whereα = αFαG andA = O(VV2), and that

α−1<p1+handα1 is not a zero-divisor. It suffices, therefore, to show thatL RA(α−1)

maps the image ofcBF[m,aF,G]to zero.

However, for each pair of integers (,)∈VV2with, 1+2hand such that F andG are not twists of each other, we know that the image ofLRA(α−1)(cBF[m,aF,G])

vanishes when restricted to (,W⊆Max(AW, by Proposition3.5.11. Since such pairs (,) are Zariski-dense in Max(A), the result follows.

Remark 7.1.3 Cf. [19, Lemma 8.1.5], which is an analogous (but rather stronger) statement in the ordinary case.

Hence the projection ofcBF[m,aF,G]toF−◦is in the image of the injection HIw1(Qp,,F−+DV1×V2(F⊗G)∗)→HIw1(Qp,,F−◦DV1×V2(F⊗G)∗).

SinceF+DV2(G)∗is isomorphic to an unramified module twisted by anA×-valued char-

acter of the cyclotomic Galois groupΓ, we may define a Perrin-Riou logarithm map for

F−+DV1×V2(FG)by reparametrising the corresponding map for its unramified twist,

exactly as in Theorem 8.2.8 of [19]. That is, if we define D(F−+M(F⊗G)∗)=F−+D(F⊗G)∗(−1−κV2)

Γ=1

,

which is free of rank 1 overO(VV2), then we obtain the following theorem: Theorem 7.1.4 There is an injective morphism ofO(VVW)-modules

L:HIw1(Qp,,F−+DV1×V2(F⊗G)∗)→D(F−+M(F⊗G)∗) ˆ⊗O(W),

with the following property: for all classical specialisations f, g ofF,G, and all characters ofΓ of the formτ =j+ηwithηof finite order and jZ, we have a commutative diagram

HIw1 Qp,,F−+DV1×V2(F⊗G)-L D(F−+ M(F⊗G)∗) ˆ⊗O(W) H1(Qp,F−+D(fg)∗(−jη)) ? - F−+Dcris(M(f?g)(εg,p))

in which the bottom horizontal map is given by ⎧ ⎪ ⎨ ⎪ ⎩ 1− αpj fβg 1− αfβg p1+j 1 if r=0 p1+j αfβg r G(ε)−1 if r>0 ⎫ ⎪ ⎬ ⎪ ⎭· ⎧ ⎨ ⎩ (−1)kj (kj)! log if jk, (jk−1)! exp∗ if j>k,

where exp∗ and log are the Bloch–Kato dual-exponential and logarithm maps, ε is the finite-order character εg,p ·η−1 of Γ, r 0 is the conductor of ε, and G(ε) =

a∈(Z/prZ)×ε(aparis the Gauss sum.

Proof The construction of the mapL is immediate from (6.2.1). The content of the theorem is that the mapLrecovers the maps exp∗and log for the specialisations ofFand G; this follows from Nakamura’s construction of exp∗and log for (ϕ,Γ)-modules. Theorem 7.1.5 (Explicit reciprocity law)If the Viare sufficiently small, then we have

"

LcBF[1F,1,G]

FωG#

=(c2−c−(k+k−2j)εF(c)−1εG(c)−1)(−1)1+jλN(F)−1Lp(F,G,1+j).

Here, Lp(F,G,1+j)denotes Urban’s3-variable p-adic L-function as constructed in[32], andεF andεG are the characters by which the prime-to-p diamond operators act onF andG.

Proof The two sides of the desired formula agree at every (k, k, j) withkV1,kV2 and 0jmin(k, k), by [18, Theorem 6.5.9]. These points are manifestly Zariski-dense,

and the result follows.

Remark 7.1.6 The construction ofωGand the proof of the explicit reciprocity law are also valid ifGis a Coleman family passing through ap-stabilisationgαof ap-regular weight 1 form, as in Theorem4.7.2; the only difference is that one may need to replaceV2with a finite flat covering ˜V2. In this setting, is automatically ordinary, soGis in fact a Hida family, and one can use the construction ofωGgiven in [19, Proposition 10.12.2]. 8 Bounding Selmer groups

8.1 Notation and hypotheses

Letf, g be cuspidal modular newforms of weightsk+2, k+2, respectively, and levels

Nf, Ngprime top. Wedopermit here the casek= −1. We suppose, however, thatk>k,

so in particulark0, and we choose an integerjsuch thatk+1jk. Ifj= k+2k+1, then we assume thatεfεgis not trivial, whereεf andεgare the characters off andg.

As usual, we letE be a finite extension ofQpwith ring of integersO, containing the

coefficients off andg. Our goal will be to bound the Selmer group associated with the Galois representationMO(fg)(1+j), in terms of theL-valueL(f, g,1+j); our hypotheses on (k, k, j) are precisely those required to ensure that thisL-value is acriticalvalue.

It will be convenient to impose the following local assumptions atp:

• (p-regularity) We haveαf =βf andαg =βg, whereαf,βf are the roots of the Hecke

polynomial off atp, and similarly forg. • (no local zero) None of the pairwise products

αfαg,αfβg,βfαg,βfβg

is equal topjorp1+j, so the Euler factor ofL(f, g, s) atpdoes not vanish ats = jor

s=1+j.

• (nobility offα) Iff is ordinary, then eitherαf is the unit root of the Hecke polynomial,

orME(f)|GQpis not the direct sum of two characters (so the eigenformis noble in

the sense of4.6.3).

• (nobility ofgα andgβ) Ifk 0, thenME(g)|GQp does not split as a direct sum of

characters, so bothp-stabilisationsgαandgβare noble.

Remark 8.1.1 (1) In our arguments we will use bothp-stabilisationsgαandgβofg, but only the onep-stabilisationfα off; in particular, we do not require that the other

p-stabilisationfβbe noble.

(2) Note that the “no local zero” hypothesis is automatic, for weight reasons, unlessk+k

is even andj= k+2k orj= k+2k +1 (so theL-valueL(f, g,1+j) is a “near-central” value).

Thep-regularity hypothesis implies that we have direct sum decompositions Dcris(ME(f)∗)=Dcris(ME(f)∗)αfDcris(ME(f)∗)βf

where ϕ acts on the two direct summands as multiplication byαf−1,βf−1, respectively, and similarly forg. This induces a decomposition ofDcris(ME(fg)∗) into four direct summandsDcris(ME(fg)∗)αfαg etc.

Definition 8.1.2 We write

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