Abstract In this paper, we give a geometric construction of the three strong non-lifted $$(3\mod 5)$$ ( 3 mod 5 ) -arcs in $${{\,\textrm{PG}\,}}(3,5)$$ PG ( 3 , 5 ) of respective sizes 128, 143, and 168, and construct an infinite family of non-lifted, strong $$(t\mod q)$$ ( t mod q ) -arcs in $${{\,\textrm{PG}\,}}(r,q)$$ PG ( r , q ) with $$t=(q+1)/2$$ t = ( q + 1 ) / 2 for all $$r\ge 3$$ r ≥ 3 and all odd prime powers q.

The statement given in the title is proved. Linear codes over chain rings (commutative and noncommutative) are a natural generalization of linear codes over finite fields and of linear codes over integer residue class rings of prime power order. In matters of linear representability there is no obvious reason why we should prefer one chain ring to the other. Yet, apart from Z/sub 4/, there is one further nontrivial chain ring with four elements: the ring Z/sub 2/[x]/(x/sup 2/) of dual numbers over Z/sub 2/. It is natural to ask about the linear representability of the Reed-Muller codes over this ring. For the sake of completeness, we reformulate here in an obvious way the definition of a linearly representable code.