Diffeo·morphisms which satisfy the Beltrami equation with a finite Beltrami coefficient have the “quasi” form of this property. A theorem of Liouville states that, in R-n with n greater than two, any function with this property is a composition of Mobius transformations. A function with this property that connects the upper half-plane to any simple (-5[1])polygon can be constructed with the Schwarz-Christoffel (-5[1])integral. Two subsets of the complex plane have this type of (*) equivalence if there is a bi·holo·morphic function connecting them; such equivalence exists between any simply connected open set and the unit disc (10[1])per the Riemann mapping theorem. For functions with this property, the Jacobian everywhere equals a scalar multiple of a rotation matrix. For 10 points, name this type of function that locally preserves (-5[1])angles. (10[1])■END■ (10[1]0[3])