A helper function for htcIdentifyStep, creates an identifier
function based on its given parameters. This created identifier function will
identify the directed edges from 'targets' to 'node.'
createHtcIdentifier(idFunc, sources, targets, node, htrSources)an identification function
identification of edge coefficients often requires that other edge coefficients already be identified. This argument should be a function that produces all such identifications. The newly created identifier function will return these identifications along with its own.
the sources of the half-trek system.
the targets of the half-trek system (these should be the
parents of node).
the node for which all incoming edges are to be identified (the tails of which are targets).
the nodes in sources which are half-trek reachable from
node. All incoming edges to these sources should be identified by
idFunc for the newly created identification function to work.
Foygel, R., Draisma, J., and Drton, M. (2012) Half-trek criterion for generic identifiability of linear structural equation models. Ann. Statist. 40(3): 1682-1713.