SCKF	Square root cubature Kalman filter
SMDE	Singular multi-pantograph differential equations
T2-FLS	Type-2 fuzzy logic system
FLS	Fuzzy logic system
NN	Neural network
MDE	Multi-pantograph differential equation
RMSE	Root mean square error
TIC	Inequality coefficient of Theil index
VAR	variance
FIT	Fitness
IR	Interquartile range
Med	Median
Min	Minimum
M	Number of rules
$m_l$	Center of l-th Gaussian membership function
${\overline{\nu }}_l$	Upper standard division
${\underset{\_}{\nu }}_l$	Lower standard division
J	Cost function
${\psi }_l$	l-th rule firing
$\varphi$	Covariance matrix
$\kappa$	Kalman gain
N	Number of data samples