Peripheric extended twists

The properties of the set (L) over cap. of extended Jordanian twists are st udied. It is shown that the boundaries of (L) over cap contain twists whose characteristics differ considerably from those of internal points. The ext ension multipliers of these 'peripheric' twists are factorizable. This lead s to simplifications in the twisted algebra relations and helps to find the explicit form for coproducts. The peripheric twisted algebra U(sl(4)) is o btained to illustrate the construction. It is shown that the corresponding deformation Up(sl(4)) cannot be connected with the Drinfeld-Jimbo one by a smooth limit procedure. All the carrier algebras for the extended and the p eripheric extended twists are proved to be Frobenius.