Jano I. van Hemert Thomas Bäck Measuring the Searched Space to Guide Efficiency: The Principle and Evidence on Constraint Satisfaction. 23-32 2002 conf/ppsn/2002 PPSN http://link.springer.de/link/service/series/0558/bibs/2439/24390023.htm db/conf/ppsn/ppsn2002.html#HemertB02