Before revision: A graphoid is defined as a dependency model that is closed under the following five axioms: Symmetry: Decomposition: Weak Union: Contraction: Intersection: A semi-graphoid is a dependency model closed under (i) – (iv).
After revision: A graphoid is defined as a dependency model that is closed under the following five axioms: Symmetry: Decomposition: Weak Union: Contraction: Intersection: A semi-graphoid is a dependency model closed under 1 –