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2-3 The Equivalence Theorem for Conformal Mappings
The equivalence theorem for conformal mappings from the left two-dimensional Riemann
manifold to the right two-dimensional Euclidean manifold (conformeomorphism), Korn-
Lichtenstein equations and Cauchy-Riemann equations (d'Alembert-Euler equations).
The previous equivalence theorem for a conformeomorphism is specialized for the case of the
two-dimensional right Euclidean manifold
{ M
r ,g μν }
=
{ R
2 μν }
=:
E
2 . In many applications,
2 μν }
l of the left
the choice of
{ R
is the planar manifold, for instance, the tangent space T U o M
two-dimensional Riemann manifold fixed to the point U 0 =
, being covered by Cartesian
or polar coordinates. For an illustration of such a setup of a “planar manifold”, go back to our
previous examples.
{
U 0 ,U 0 }
2-31 Conformeomorphism
First, let us confront you with Lemma 2.3 . The proof based upon Theorem 1.11 is straightforward.
Examples are given in the following chapters.
2
2 μν
Lemma 2.3 (Conformeomorphism, conformal mapping, special case
{ M
r ,g μν
}
=
{ R
}
).
2
2 μν
Let f :
M
l →{ R
}
be an orientation preserving conformal mapping. Then the following
conditions are equivalent.
(i) Ψ l ( ˙
1 , ˙
U
U
2 )= Ψ r ( ˙
u
1 , ˙
u
2 )
(2.18)
˙
1 , ˙
for all tangent vectors
U
U
2 and their images ˙
u
1 , ˙
u
2 , respectively.
(ii) C l = λ 2 ( U 0 )G l versus C r = λ 2 I 2 , C r =I 2 2 ,
C 11 = C 22 = λ 2 , C 12 = C 21 =0 , C 11 = C 22 = λ 2 , C 12 = C 21 =0;
(2.19)
E l = K ( U 0 )G l versus E r = κ I 2 , E r =I 2 /κ,
E 11 = E 22 = κ, E 12 = E 21 =0 , E 11 = E 22 = κ 1 , E 12 = E 21 =0 .
(iii) K =( Λ 2
( λ 2
,
1) / 2
Λ 2 =2 K +1
1) / 2= κ
2 κ +1= λ 2
versus
Λ 1 = Λ 2 = Λ ( U 0 )versus λ 1 = λ 2 = λ ( u 0 ) ,
(2.20)
K 1 = K 2 = K ( U 0 ) s κ 1 = κ 2 = κ ( u 0 ) ,
Λ 2 ( U 0 ) = tr[C l G l ] / 2 s λ 2 ( u 0 ) = tr[C r ] / 2;
(left dilatation) K = tr[E l G l ] / 2
versus (right dilatation) κ = tr[E r ] / 2 ,
tr[C l G l ]=2 det [C l G l ]
tr[C l G l ]=2 det [C r ] ,
versus
(2.21)
tr[E l G l ]=2 det [E l G l ]
tr[E r ]=2 det [E r ] .
versus
 
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