"SymmetryProblem""SymmetryProblem" represent the data structure
corresponding to a symmetry problem.x and y are data frames containing the variables
$\mathbf{X}$ and $\mathbf{Y}$ respectively, block is an
optional factor representing the block structure $b$ and weights is
an optional integer vector corresponding to the case weights $w$."IndependenceProblem ", directly.