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4.2. Proposition. For a generic choice of gΘ , H1, H2, the space M Θ Φ (γ, x) - if non-empty - is a<br />

manifold of dimension<br />

These manifolds carry coherent orientations.<br />

dimM Θ Φ (γ, x) = m Θ (γ) − µ Θ (x).<br />

The inequality (49) implies the energy estimate which can be used to prove C∞ loc compactness of<br />

the space M Θ Φ (γ, x). When µΘ (x) = mΘ (γ), the space M Θ Φ (γ, x) consists of finitely many oriented<br />

points, which define an integer nΘ Φ (γ, x). These integers are the coefficients of a homomorphism<br />

Φ Θ L1⊕L2 : Mk(ËΘ<br />

, g L1⊕L2 Θ ) → Fk(H1 ⊕ H2, J), γ ↦→ �<br />

n Θ Φ (γ, x)x.<br />

x∈P Θ (H1⊕H2)<br />

µ Θ (x)=k<br />

This is a chain complex isomorphism. See [APS08] for the construction of this isomorphism for<br />

arbitrary non-local conormal boundary conditions.<br />

4.2 The Ω ring isomorphism<br />

Let L1, L2 ∈ C ∞ ([0, 1] × TM) be two Lagrangians such that L1(1, ·) = L2(0, ·) with all the time<br />

derivatives, and such that L1 and L2 satisfy (L0) Ω , (L1), (L2), and (24). Assume also that the<br />

Lagrangian L1#L2 defined by (23) satisfies (L0) Ω . Let H1 and H2 be the Fenchel transforms of<br />

L1 and L2, so that H1#H2 is the Fenchel transform of L1#L2, and the three Hamiltonians H1,<br />

H2, and H1#H2 satisfy (H0) Ω , (H1), (H2).<br />

In section 2.6 we have shown how the Pontrjagin product can be expressed in a Morse theoretical<br />

way. In other words, we have constructed a homomorphism<br />

M# : Mh(ËL1, g1) ⊗ Mj(ËL2, g2) −→ Mh+j(ËL1#L2, g)<br />

such that the upper square in the following diagram commutes<br />

Hh(Ω(M, q0)) ⊗ Hj(Ω(M, q0))<br />

∼=<br />

��<br />

HMh(ËΩ , g1) ⊗ HMj(ËΩ , g2)<br />

L1 L2<br />

HΦ Ω<br />

L 1 ⊗HΦ Ω<br />

L 2<br />

��<br />

HF Ω h (H1, J) ⊗ HF Ω j (H2, J)<br />

#<br />

HM#<br />

HΥ Ω<br />

��<br />

��<br />

Hh+j(Ω(M, q0))<br />

��<br />

∼=<br />

HMh+j(ËΩ L1#L2 , g)<br />

HΦ Ω<br />

L 1 #L 2<br />

��<br />

��<br />

HF Ω h+j (H1#H2, J)<br />

The aim of this section is to show that also the lower square commutes. Actually, we will show<br />

more, namely that the diagram<br />

� M(ËΩ L1 , g1) ⊗ M(ËΩ L2 , g2) �<br />

Φ Ω<br />

L 1 ⊗Φ Ω<br />

L 2<br />

� ��<br />

Ω F (H1, J) ⊗ F Ω (H2, J) �<br />

k<br />

k<br />

M#<br />

Υ Ω<br />

��<br />

Mk(ËΩ L1#L2 , g)<br />

Φ Ω<br />

L 1 #L 2<br />

��<br />

��<br />

F Ω k (H1#H2, J)<br />

is chain-homotopy commutative. Instead than constructing a direct homotopy between ΦΩ L1#L2 ◦<br />

M# and ΥΩ ◦ ΦΩ L1 ⊗ ΦΩ , we shall prove that both chain maps are homotopic to a third one, that<br />

L2<br />

we name KΩ , see Figure 4.<br />

The definition of KΩ is based on the following space of solutions of the Floer equation for the<br />

Hamiltonian H defined in (40): given γ1 ∈ PΩ (L1), γ2 ∈ PΩ (L2), and x ∈ PΩ (H1#H2), let<br />

M Ω K (γ1, γ2; x) be the space of solutions of the Floer equation<br />

∂J,H(u) = 0,<br />

40

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