All mirror transformations we will use later will be of the type µ f , ν g as above. Moreover, all Euler **data** we will encounter will have property (i) of Theorem 5.4. The transformations µ f , ν g clearly preserve this property. Since A is linked to B, it follows thatÃ is linked toB. By Theorem 5.4, we conclude that A =B. Now our assertion follows from eqns. (6.6).