Defective dual varieties for real spectra

• DOI: 10.1007/s10801-018-0816-4
• Publication Date: 2018-02-27T10:44:28Z
• Authors: Jens Forsgård
• Keywords: Mathematics - Algebraic Geometry; FOS: Mathematics; Mathematics - Combinatorics; Combinatorics (math.CO); Algebraic Geometry (math.AG)

We introduce an invariant of a finite point configuration $$A \subset \mathbb {R}^{1+n}$$ which we denote the cuspidal form A. use this to extend Esterov’s characterization dual-defective configurations exponential sums; dual variety associated with A has codimension at least 2 if and only does not contain any iterated circuit.