Parametric restrictions on quasi-symmetric designs

In this paper, we attach several new invariants to connected strongly regular graphs (excepting conference on non-square number of vertices): one invariant called the discriminant, and a p-adic corresponding each prime p. We prove parametric restrictions quasi-symmetric 2-designs with given block graph G defect (absolute difference two intersection numbers) solely in terms parameters G, including these invariants. This is natural analogue Schutzenberger’s Theorem Shrikhande–Chowla–Ryser theorem. theorem effective when can be explicitly computed. do for complete multipartite graphs, co-triangular symplectic non-orthogonality (over field order 2) Steiner yielding explicit whose belong any four classes.