# Executable Multivariate Polynomials

 Title: Executable Multivariate Polynomials Authors: Christian Sternagel, René Thiemann (rene /dot/ thiemann /at/ uibk /dot/ ac /dot/ at), Alexander Maletzky, Fabian Immler, Florian Haftmann, Andreas Lochbihler and Alexander Bentkamp (bentkamp /at/ gmail /dot/ com) Submission date: 2010-08-10 Abstract: We define multivariate polynomials over arbitrary (ordered) semirings in combination with (executable) operations like addition, multiplication, and substitution. We also define (weak) monotonicity of polynomials and comparison of polynomials where we provide standard estimations like absolute positiveness or the more recent approach of Neurauter, Zankl, and Middeldorp. Moreover, it is proven that strongly normalizing (monotone) orders can be lifted to strongly normalizing (monotone) orders over polynomials. Our formalization was performed as part of the IsaFoR/CeTA-system which contains several termination techniques. The provided theories have been essential to formalize polynomial interpretations. This formalization also contains an abstract representation as coefficient functions with finite support and a type of power-products. If this type is ordered by a linear (term) ordering, various additional notions, such as leading power-product, leading coefficient etc., are introduced as well. Furthermore, a lot of generic properties of, and functions on, multivariate polynomials are formalized, including the substitution and evaluation homomorphisms, embeddings of polynomial rings into larger rings (i.e. with one additional indeterminate), homogenization and dehomogenization of polynomials, and the canonical isomorphism between R[X,Y] and R[X][Y]. Change history: [2010-09-17]: Moved theories on arbitrary (ordered) semirings to Abstract Rewriting. [2016-10-28]: Added abstract representation of polynomials and authors Maletzky/Immler. [2018-01-23]: Added authors Haftmann, Lochbihler after incorporating their formalization of multivariate polynomials based on Polynomial mappings. Moved material from Bentkamp's entry "Deep Learning". [2019-04-18]: Added material about polynomials whose power-products are represented themselves by polynomial mappings. BibTeX: @article{Polynomials-AFP, author = {Christian Sternagel and René Thiemann and Alexander Maletzky and Fabian Immler and Florian Haftmann and Andreas Lochbihler and Alexander Bentkamp}, title = {Executable Multivariate Polynomials}, journal = {Archive of Formal Proofs}, month = aug, year = 2010, note = {\url{https://isa-afp.org/entries/Polynomials.html}, Formal proof development}, ISSN = {2150-914x}, } License: GNU Lesser General Public License (LGPL) Depends on: Abstract-Rewriting, Matrix, Show, Well_Quasi_Orders Used by: Deep_Learning, Factor_Algebraic_Polynomial, Groebner_Bases, Lambda_Free_KBOs, PAC_Checker, Symmetric_Polynomials, Virtual_Substitution