The structure of the monoid of autarkies for clause-sets is investigated (autarkies are generalizations of satisfying (truth) assignments). The notion of a \plain clause-set" is introduced, where every clause is usable by some resolution refutation, and it is shown that a clause-set is plain ii it has no non-trivial autarky. Every clause-set has a unique decomposition into a plain sub-clause-se...

sumes responsibility for the teaching of mentally handicapped children and the training of their teachers. On the surface, taking over from the Department of Health appeared to involve a minor readjustment, in fact repercussions have been loud and farreaching. Stanley Segal, principal of Ravenswood Centre for Special Education, clarifies the complexities and warns that the wrangles must be reso...

Distal propulsion of a 28 mm umbrella filter from vena cava to femoral vein occurred in a 75-year-old woman during external cardiac massage. After cardiac massage, filter position must be checked roentgenographically. Optimal management of distal migration might include placement of a second umbrella to prevent recurrent emboli and proximal migration of the dislodged umbrella.