While reading the Hovey Model Category I learned that $I^{rlr} = I^r$ and $I^{lrl} = I^l$ for any setevery class of morphisms $I$ morphisms. What other relations are there between the operations of taking (weak) orthogonals? Are all $I^l, I^{ll}, I^{lll}, I^{llll}, ..$ distinct in general?