Auxiliary Lemmas

In order to estimate the error z = y — u, we shall need an auxiliary lemma. 

As further developments occur, we need an auxiliary lemma. 

To continue the proof, we introduce two following auxiliary Lemmas ... 

Let be fixed. Before proving the theorem an auxiliary statement is to be established. It is formulated as a lemma. 

The final result is that the sensitivities can be obtained from the scalar product of the original electric field and the auxiliary electric fields, generated by elementary electric or magnetic dipole current sources, located at the receiver position, r. This result was originally demonstrated by Pellerin et al., 1993, and then a derivation based on Lorentz lemma was given by McGillivray et al., 1994. 

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