A Method to Extract Causality for Safety Events in Chemical Accidents from Fault Trees and Accident Reports
Table 1
Notations and meanings.
Notation
Meaning
FT (V, G, E, v0)
Fault tree, where V is the set of nodes, G is the set of gates, E is the set of edges, and is the root node
VM, VL
Set of intermediate nodes and set of leaf nodes
EEG = (V, E)
The expression of event evolutionary graph, where V is the set of nodes and E is the set of edges
Ψ(.)
The function that returns the input events for a given logic gate
(.)
The function that returns the output event for a given logic gate
e = {o, ,p, t}
Event e, where o, ,p, and t are used to represent the event participants, event trigger word, location, and timestamp of event occurrence, respectively
SRL(.)
Semantic role labeling function
SDP(.)
Semantic dependency parsing function
DP(.)
Dependency parsing function
πF(S, e)
The function to judge whether e fails given the set S of failed BE
P(.)
Probability function
Pc(., .)
The cooccurrence probability function
PMI
Pointwise mutual information
zt
The update gate of GRU unit
rt
The reset gate of GRU unit
xt
The input of GRU unit
ht
The hidden layer information at the current moment
ht-1
The hidden layer information at the previous moment
The candidate hidden layer information at the current moment
W
The weight matrix
σ
The sigmoid activation function
tanh
The tanh activation function
⊕
The vector concatenating function
αit
The normalized word weight of sentence si
si
The sentence vector
ui
The hidden representation of sentence vector si
αi
The normalized sentence weight of sentence set Sepq
