Algorithm 1 Three-way decision model based on the triangular fuzzy similarity

Input: target domain data $X_t$, threshold $\delta$, $\alpha$ and $\beta$.

Output: positive region object set $Pos(X)$, negative region object set $Neg(X)$, boundary region object set $Bnd(X)$.

1: BEGIN

2: Calculate the degree of information difference $I{D}_i(a_j,a_k)$ of each object in the target domain under any two attributes according to Equation (15).

3: Calculate the triangular fuzzy similarity ${\tilde{S}}_{TF}({\tilde{x}}_i,{\tilde{x}}_k)$ between any two objects in the target domain using Equation (17).

4: According to Equation (21), divide the target domain $X_t$ into three domains.

5: END BEGIN