Systems and methods are disclosed to determine “don't care” variables in programming code. The method comprises obtaining an SMT formula having a plurality of SMT variables from programming code; obtaining a simplified SMT formula from the SMT formula, the simplified SMT formula includes a plurality of simplified SMT variables; obtaining an SAT formula from the simplified SMT formula, the SAT formula includes a plurality of SAT variables; determining which of the plurality of the SMT variables are “don't care” variables from the simplified SMT formula; and determining which of the plurality of the SMT variables are “don't care” variables from the simplified SAT formula.