New records of genera and species of spider wasps (Hymenoptera: Pompilidae) from Colombia are provided. Agenioideus, Cryptocheilus, Evagetes, Mystacagenia, and Xerochares are newly recorded genera from Colombia. Nineteen species are first recorded from Colombia: Aimatocarevitrea (Fox); Ageniellaazteca (Cameron); Ageniellacurtipinus (Cameron); Ageniellafallax (Arlé); Ageniellahirsuta Banks; Agen...

New examples of Cameron-Liebler line classes in PG(3,q) are given with parameter 1 2 (q 2− 1). These examples have been constructed for many odd values of q using a computer search, by forming a union of line orbits from a cyclic collineation group acting on the space. While there are many equivalent characterizations of these objects, perhaps the most significant is that a set of lines L in PG...

AMONG TE lives of the many men and women who have been qualified to practise the art of medicine are a number who have moved from that discipline into others where they have made a name and reputation for themselves which they might not have attained to had they remained loyal to their first choice: yet they have brought to their other work something which they learned in the days when their fi...

A subset A of the integers is said to be sum-free if there do not exist elements x, y, z ∈ A with x+y = z. It is shown that the number of sum-free subsets of {1, . . . , N} is O(2N/2), confirming a well-known conjecture of Cameron and Erdős.