Sui q-archi completi in piani proiettivi di ordine q pari

Let \pi_q be a non desarguesian projective plan of even order q containing a complete q-arc K. Assume that K admits a point P such that there are exactly q-h (h even, 4 \leq h \leq q-6) tangents to K through P. In this paper first we prove that the maximum index of any further point of \pi_q is 2h, then we study the q-arcs such that any point of \pi_q has index 0, 2, 4 or 2h and finally we obtain bounds for the order of \pi_q.