normal Z the sum of the absolute values of the components of Z to make this small you have to basically make many of the components of Z zero as many as possible and so you end up with sparse sparse representation and that actually limits the the volume of space that is the has low energy essentially this is this is what what you get so this is sort of the unconditional version of it where there is no X is you just modeling Y and here I give you a Y Z the regular as before Z is the other one norm Z is multiplied by a matrix color item matrix