A Method to Extract Causality for Safety Events in Chemical Accidents from Fault Trees and Accident Reports

Algorithm 1

The CEFTAR algorithm.

	Input: the set of fault trees (FTS) and accident reports (ARS).
	Output: the set of event pairs with causality (ECS).
(1)	Construct the set of events (ES) and event pairs (EPS).
(2)	ECS = EPS = ES = Φ;
(3)	Achieve word segmentation for ARS by the tool “Jieba” and build the corpus CA;
(4)	For each word w in CA, train a vector for w by “Word2vec”;
(5)	For each ft  FTS
(6)	For each ne  ft.E
(7)	{Identify the event e in the node ne;
(8)	ES = ES ∪ {e}; }
(9)	For ∀ei and ej  ES, build event pair <ei, ej> and EPS = EPS ∪ {<ei, ej>};
(10)	For each <ei, ej> EPS
(11)	If   ft.G, s.t.: ei  I()∧ej  O() or ej  I()∧ei  O() then ECS = ECS ∪ {<ei, ej>};
(12)	Else { construct ISFeij and use ve represent the vector of ISFeij
(13)	compute Seij;
(14)	For each Sep sentence in Seij
(15)	Build the vector sp for Sep, Sp = Σαithit;
(16)	Generate the vector vs. for Seij;  = ΣαiSi;
(17)	y = argmax(softmax(( + )));
(18)	if (y = = 1) then ECS = ECS∪{<ei, ej>}; }
(19)	Return (ECS)
(20)	}