Uses of Slack, Surplus and Artificial variables in LPP. (Apr 2004)
Slack variable: It is used o convert a Less than or equal to (≤) constraint into equality to write standard form. It is ADDED to ≤ constraint.
E. g. 2×1 + 4×2 ≤ 40 will become 2×1 + 4×2 + S1 = 40. Where, S1 is slack variable.
Surplus & Artificial variables: They are used to convert Greater than or equal to (≥) constraint into equality to write standard form. Surplus variable is SUBTRACTED from ≥ constraint and Artificial variable is ADDED to the ≥ constraint.
E. g. 2×1 + 4×2 ≥ 40 will become 2×1 + 4×2 – s1 + A1 = 40. s2 is surplus variable and A1 is artificial variable.