Dominance-Partitioned Subgraph Matching on Large RDF Graph

Algorithm 2

DPPG-construction algorithm.

	Input: a pattern graph
	Output: a dominance-partitioned pattern hypergraph
(1)	i = 0, DFS[ur] = i,  ⟵ ur;
(2)	For u ∈ ur.successors do
(3)	If u is unvisited then;
(4)	DFS[u] = i++, Continue to ur.successors;
(5)	Else if u is visited then
(6)	⟵ u;
(7)	For DFS[u] = I from to 0 do
(8)	For u′ ∈ u.precursors do
(9)	If DFS[u] ∈ DFS[u′] then
(10)	⟵ (u, u′), Continue to u′.precursors;
(11)	Else if sdom[u] > sdom[u′] then
(12)	⟵ (u, u′), sdom[u] = sdom[u′];
(13)	⟵ |sdom[u], u);
(14)	For u ∈  in descending order of DFS do
(15)	For u′ ∈  − u do
(16)	If DFS [u] < DFS [u′] < DFS [sdom[u]] then
(17)	Removing u from ;
(18)	For u ∈ do
(19)	⟵ (u, u.precursors),  =  ∪ ;
(20)	For u ∈  and u′ ∈  − u do
(21)	If ∧  ≠ ∅ then
(22)	⟵ (u, u′);
(23)	Return;