 In other words, in the case that "G" has one-dimensional center, we assume that the semisimple part does "not" act prehomogeneously; it follows that there is a "relative invariant", i.e., a function invariant under the semisimple part of "G", which is homogeneous of a certain degree "d".This makes it possible to restrict attention to semisimple "G" ≤ SL("V") and split the classification as follows