Paul Beame Russell Impagliazzo Toniann Pitassi Nathan Segerlind Formula Caching in DPLL. 2006 13 Electronic Colloquium on Computational Complexity (ECCC) http://eccc.hpi-web.de/eccc-reports/2006/TR06-140/index.html 140 db/journals/eccc/eccc13.html#BeameIPS06