Building the Implication Graph

For each customer's clause "a OR b", add two edges to the implication graph: NOT a → b and NOT b → a. This is the standard conversion. Example: customer wants "$+1$ $-2$" (topping $1$ on, topping $2$ off). The clause is $x_1$ OR NOT $x_2$.

Add edges: NOT $x_1$ → NOT $x_2$ and $x_2$ → $x_1$. If topping $1$ is off, topping $2$ must be off. If topping $2$ is on, topping $1$ must be on. Build the full graph from all m customer constraints.