For a given nonempty subset L of the line set of the projective plane PG(2,q), a blocking set with respect to L (or simply, an L-blocking set) is a subset B of the point set of PG(2,q) such that every line of L contains at least one point of B. Let E (respectively; T, S) denote the set of all lines which are external (respectively; tangent, secant) to an irreducible conic in PG(2,q). We shall discuss minimum size L-blocking sets of PG(2,q) for L = E, S, T, SUT, EUT, SUE.
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Blocking sets of PG(2,q) with respect to a conic