This paper studies the sensitivity to the observations of the block/group Lasso solution to an overdetermined linear regression model. Such a regularization is known to promote sparsity patterns structured as nonoverlapping groups of coefficients. Our main contribution provides a local parameterization of the solution with respect to the observations. As a byproduct, we give an unbiased estimat...

The collective description of the octupole degrees of freedom has been a long standing problem in nuclear physics @1#. The phenomenological description of low-energy vibrational states @2,3# discussed them in terms of simple ‘‘surface modes’’ thus allowing for the description of the octupole degrees of freedom in terms of seven collective variables a3m @2,4#. In the 1980s, theoretical calculati...