Generalized Quadrangle - Classical Generalized Quadrangles

Classical Generalized Quadrangles

When looking at the different cases for polar spaces of rank at least three, and extrapolating them to rank 2, one finds these (finite) generalized quadrangles :

  • A hyperbolic quadric, a parabolic quadric and an elliptic quadric are the only possible quadrics in projective spaces over finite fields with projective index 1. We find these parameters respectively :
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  • A hermitian variety has projective index 1 if and only if n is 3 or 4. We find :
  • A symplectic polarity in has a maximal isotropic subspace of dimension 1 if and only if . Here, we find a generalized quadrangle, with .

The generalized quadrangle derived from is always isomorphic with the dual of, and they are both self-dual and thus isomorphic to each other if and only if is even.

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