can also be viewed as an isomorphism , where is the opposite ring of , which has the same underlying set and the same addition, but whose multiplication operation () is defined by , where the product on the right is the product in . It follows from this that a right (left) -module can be turned into a left (right) -module, . Thus, the sesquilinear form can be viewed as a bilinear form . See also *-ring Notes References External links Functional analysis Linear algebra