We define the orthogonal sum of quadratic pairs and we show that there is no Witt cancellation theorem for this operation in characteristic 2. 1. Introduction. Quadratic pairs on central simple algebras were defined in [5]. They play the same role for quadratic forms as involutions for symmetric or skew-symmetric bilinear forms. In particular, they can be used to define twisted orthogonal group...

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vegetation deterioration is a main cause of erosion and land degradation. therefore, land cover reclamation in the effected areas will affect erosion trend. in reclamation projects, the investigation of relationship between the planted species and soils is highly recommended. atriplex species can sequester carbon into soil, and have an ability to conserve soil and prevent soil erosion, as well....