For a directed network, only dyads \((i,j)\) for
which \(i < j\) may be toggled. Optional argument attr
controls which subgraphs are thus restricted.
# upper_tri(attr = NULL)
a vertex attribute specification (see Specifying Vertex attributes and Levels (?nodal_attributes
) for details.)
ergmConstraint
for index of constraints and hints currently visible to the package.
ergm:::.formatTermKeywords("ergmConstraint", "upper_tri", "subsection")