3.1.9. pywhy_graphs.algorithms.check_pag_definition

pywhy_graphs.algorithms.check_pag_definition(G: PAG, L: set | None = None, S: set | None = None)

Checks if the provided graph is a valid Partial Ancestral Graph (PAG).

A valid PAG as defined in [1] is a mixed edge graph that has no directed or almost directed cycles and no inducing paths between any two non-adjacent pair of nodes. It is graph representing all conditional independence (CI) statements that are present in a DAG, forming an equivalence class of DAGs that encode the same CI statements.

The steps involved in this check are as follows:

• Check for any directed cycles in the PAG.

• Check for any almost directed cycles in the PAG.

• For every pair of non-adjacent nodes, check for inducing paths.

Parameters:

GGraph

The graph.

Returns:

is_validbool

A boolean indicating whether the provided graph is a valid PAG or not.