Brain will not function today - stuck on FOUR. 12d Based on theoretical deduction (1,6) I have ?,P?I???. 21a Mathematician in the pensions field (7) I have ???U???. 22d Way in which you may have to reverse (3-2-3) I have ??L-?E-?A?. 41a Stay for a while (7) I have ?O?E?R?.TIA.