trekSeparationIdentifyStep: Perform one iteration of trek separation identification.

In SEMID: Identifiability of Linear Structural Equation Models

Perform one iteration of trek separation identification.

Description

A function that does one step through all the nodes in a mixed graph and tries to identify new edge coefficients using trek-separation as described in Weihs, Robeva, Robinson, et al. (2017).

Usage

trekSeparationIdentifyStep(
  mixedGraph,
  unsolvedParents,
  solvedParents,
  identifier,
  maxSubsetSize = 3
)

Arguments

mixedGraph	a MixedGraph object representing the mixed graph.
unsolvedParents	a list whose ith index is a vector of all the parents j of i in G which for which the edge j->i is not yet known to be generically identifiable.
solvedParents	the complement of unsolvedParents, a list whose ith index is a vector of all parents j of i for which the edge i->j is known to be generically identifiable (perhaps by other algorithms).
identifier	an identification function that must produce the identifications corresponding to those in solved parents. That is identifier should be a function taking a single argument Sigma (any generically generated covariance matrix corresponding to the mixed graph) and returns a list with two named arguments Lambda denote the number of nodes in mixedGraph as n. Then Lambda is an nxn matrix whose i,jth entry equals 0 if i is not a parent of j, equals NA if i is a parent of j but identifier cannot identify it generically, equals the (generically) unique value corresponding to the weight along the edge i->j that was used to produce Sigma. Omega just as Lambda but for the bidirected edges in the mixed graph such that if j is in solvedParents[[i]] we must have that Lambda[j,i] is not NA.
maxSubsetSize	a positive integer which controls the maximum subset size considered in the trek-separation identification algorithm. Making this parameter smaller means the algorithm will be faster but less exhaustive (and hence less powerful).

Value

see the return of htcIdentifyStep.

SEMID documentation built on July 26, 2023, 5:40 p.m.