x(t)↔FSak,y(t)↔FSbkx(t) \xleftrightarrow{FS} a_k, y(t) \xleftrightarrow{FS} b_kx(t)FSak,y(t)FSbkx(t)y(t)↔FSak∗bkx(t)y(t) \xleftrightarrow{FS} a_k \ast b_kx(t)y(t)FSak∗bk ∑lalbk−l=ak∗bk\sum_l a_l b_{k-l} = a_k \ast b_k∑lalbk−l=ak∗bk
