Table 2. Features and symbols description.

Symbol	Features	Encoding
Y	Initial rating	A–F:1–6
$X1$	Loan amount	–
$X2$	Borrowing term	–
$X3$	Borrowing rate	–
$X4$	Borrowing type	‘Ecommerce’: 1, ‘APP’: 2, ‘Ordinary’: 3, and ‘Other’: 4
$X5$	First flag	Yes:1, No:0
$X6$	Age	–
$X7$	Gender	Male: 1, Female: 2
$X8$	Mobile phone authentication	Success: 1, Failure: 0
$X9$	Account authentication	Success: 1, Failure: 0
$X10$	Video authentication	Success: 1, Failure: 0
$X11$	Education certification	Success: 1, Failure: 0
$X12$	Credit authentication	Success: 1, Failure: 0
$X13$	Taobao.com certification	Success: 1, Failure: 0
$X14$	Historical number of successful loans	–
$X15$	Historical amount of successful borrowing	–
$X16$	History total outstanding amount	–
$X17$	Number of historical normal repayment periods	–
$X18$	Number of historical default periods	–
$X19$	Historical normal repayment rate	–
$X20$	Historical default repayment rate	–