Volume 16, Number 1, January 2022, 105-141. https://doi.org/10.52547/cgasa.16.1.105 Quadratic structures associated to (multi)rings K.M.d.A. Roberto, H.R.d.O. Ribeiro, and H.L. Mariano Abstract. We consider certain pairs (A, T ) where A is a (multi)ring and T A is a multiplicative set that generates, by a convenient quotient con- struction, a (multi)structure that supports a quadratic form theory: with some natural hypotheses we generalize constructions previously presented in [3] and [6]. This also provides some steps towards an abstract formally real quadratic form theory (non necessarily reduced) were the forms have general coefficients (non only units). 1 Introduction In [3], [5] and [6] are considered abstract theories of quadratic forms: spe- cial groups and real semigroups. The former treats simultaneously reduced and non-reduced theories but focuses on rings with a good amount of in- vertible coefficients to quadratic forms. The latter has the advantage of potentially consider general coefficients of a ring, but only addresses the * Corresponding author Keywords : Quadratic forms, special groups, real semigroup, multirings, hyperfields. Mathematics Subject Classification [2010]: 11Exx, 11E81. Received: 16 January 2021, Accepted: 15 May 2021. ISSN: Print 2345-5853, Online 2345-5861. © Shahid Beheshti University 105