Richard Banach Czeslaw Jeske Michael Poppleton Susan Stepney Retrenching the Purse: The Balance Enquiry Quandary, and Generalised and (1, 1) Forward Refinements. 29-69 2007 77 Fundam. Inform. 1-2 http://iospress.metapress.com/content/435211547t0v3m63/ db/journals/fuin/fuin77.html#BanachJPS07