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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Sustainable development is a development that meets the needs of present generation while not compromising the ability of future generations to also meet their needs. There are 2 cases of sustainability. Case-1 is due to the discrepancy of environment and Case-2 is due to the change of environment. User, usage context and cultural aspects play important roles in the sustainability of system. Di...