  We introduce a duality of Landau-Ginzburg models based on the notion of the
discrete Legendre transform given by Gross-Siebert. It generalizes the duality
used to construct mirrors of complete intersections in toric varieties in a
recent joint work with Gross and Katzarkov. We discuss how it appears as a
limit version of the semi-flat Strominger-Yau-Zaslow construction of mirror
symmetry with potential given as the obstruction in Floer theory.
