c	specific heat
${\mathbf{d}}^i$	i-th vector in orthogonal base in HJ method
f	additional source term
$f_{i,j}^k$	value of function f in point $(t_k,x_i,y_j)$
g	auxiliary coefficient to determine $\omega$
I	number of iterations in ACO algorithm
J	objective function
$K_i$	i-th measurement point
L	number of pheromone spots in ACO algorithm
$L_x$	length in x-direction
$L_y$	length in y-direction
$M_x$	mesh size in x-direction
$M_y$	mesh size in y-direction
n	number of sought parameters in ACO algorithm
$nT$	number of threads in ACO algorithm
N	mesh size in time
$r_{i,j}^x,r_{i,j}^y$	coefficients of matrices $R_x,R_y$
$R_x,R_y$	auxiliary matrices to to describe the solution of a direct problem
t	time
u	state function (temperature)
$u_{i,j}^k$	value of state function in point $(t_k,x_i,y_j)$
q	parameter in ACO algorithm
x	spatial variable
$x_i$	value of x variable for $i\mathsf{\Delta }x$
${\mathbf{x}}^0$	starting point in HJ method
y	spatial variable
$y_j$	value of y variable for $j\mathsf{\Delta }y$
T	final moment of time
$t_k$	value of time for $k\mathsf{\Delta }t$
Greek Symbols
$\alpha$	order of derivative in x-direction
$\beta$	order of derivative in y-direction
$\mathsf{\Gamma }$	gamma function
${\delta }_x^{\alpha },{\overline{\delta }}_x^{\alpha +1},{\delta }_y^{\beta },{\overline{\delta }}_y^{\beta +1}$	auxiliary operators to describe the solution of a direct problem
$\mathsf{\Delta }t$	time step
$\mathsf{\Delta }x$	step mesh in x-direction
$\mathsf{\Delta }y$	step mesh in y-direction
$\lambda$	thermal conductivity
${\lambda }_{i,j}$	value of thermal conductivity in point $(x_i,y_j)$
$\phi$	temperature in $t=0$
$\varrho$	mass density
$\xi$	stop criterion in HJ method
$\tau$	steps length vector in HJ method
$\omega$	weight in shifted Grünwald formula
$\mathsf{\Omega }$	domain of differential equation