TY  CONF
TI  Dual problem
KW  dual problem
KW  linear programming
KW  direct problem
KW  duality theorem
KW  graphical method
KW  normal
KW  level lines
KW  optimal solution
KW  constraint system
KW  strict inequality
JO  Mathematics in Economics
AU  Sinditskaya, E.A.
PY  2026
PB  AUS PUBLISHERS