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8.1 Pseudodifferential Operators on Boundary Manifolds  415

                                                                              (−1)
                                 χ r∗ v  := v ◦ T r  maps v given on O r to v ◦ χ r  ,
                                                     afunctionon U r ;
                                                                                        (8.1.3)
                                  χ u              maps u given on U r to u ◦ χ r ,
                                   ∗
                                   r   := u ◦ χ r
                                                     afunctionon O r ⊂ Γ,
                           are defining the pushforward χ r∗ and pullback χ , respectively.
                                                                         ∗
                                                                         r
                                                                       k
                              Afunction v on Γ is said to be in the class C (Γ) if for every chart the
                                                                     k
                           pushforward has the property v ◦ T r = χ r∗ v ∈ C (U r ).Hence,
                                                   : C (O r )  →   C (U r ) ,
                                                                    ∞
                                                       ∞
                                              χ r∗
                                                                                        (8.1.4)
                                               χ ∗  : C (U r )  →  C (O r )
                                                       ∞
                                                                     ∞
                                                r
                           and
                                                       ∞
                                                                    ∞
                                                   :  C (O r )  →  C (U r ) ,
                                              χ r∗     0            0
                                                                                        (8.1.5)
                                               χ ∗ r  :  C (U r )  → C (O r ) .
                                                       ∞
                                                                    ∞
                                                       0
                                                                    0
                           In addition, we require the following smoothing property to be satisfied: If
                           ϕ, ψ ∈ C (Γ) with supp ϕ∩supp ψ = ∅ then the composition ϕAψ• extends
                                    ∞
                                    0
                                                                         ∞
                           to a smoothing operator on Γ, i.e., for every u ∈ C (Γ) one has ϕAψu ∈
                             ∞
                           C (Γ).
                              An immediate consequence of these definitions is the following theorem.
                                                    m
                           Theorem 8.1.1. Let A ∈L (Γ) and let A = {(O r ,U r ,χ r ) | r ∈ I} be an
                           atlas on Γ. Then for every pair of charts (O r ,U r ,χ r ) , (O t ,U t ,χ t ) and the
                           induced mapping Φ rt in (8.1.1), the induced local pseudodifferential operators
                           satisfy the compatibility relations
                                            ∗          ∗
                                                       r
                                            t
                                           χ A χ t  χ t∗ = χ A χ r  χ r∗ = A on D(O rt )  (8.1.6)
                           and

                                                                      )
                                         ∗        ∗           ∗
                                         r        t           rt
                               A χ t  = χ t∗ χ A χ r  χ r∗ χ = Φ rt∗ A χ r Φ  =(A χ r Φ rt  on  D χ t (O rt ) ;
                                                                                        (8.1.7)
                           (see Remark 6.1.4).



                           Fig. 8.1.1. The local surface representation.
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