Retired electronics application engineer (originally telecomm mux stuff then microprocessor control apps), software design engineer (e.g., 80's, did communications software for email app in 1984 on multitasking platform, C and 8088 assembly), IT business owner (retired), former musician and recording engineer (search on "Dalton Bentley music"), original matriculation psychology, subsquent EE. Writer/editor (various venues, include computer user group journal editor 2003 - 2010). Martial artist (now more physical therapy than threat) Polymath (original university study in psychology and sociology, continued those fields, among others) and irritant, grin. Latest work a tutorial for those new to the Isabelle Proof Assistant (a LaTex typeset document with plenty of screen shots, as well as cites): Isabelle Tutorial