Mainstream description logics systems and ontology web languages
provide a rich supply of concept operators, but there is currently little
support for complex role operators. Role negation in particular cannot 
be handled by current tableau decision procedures and is not supported 
by the standard web ontology languages.  We define a sound and 
complete tableau calculus for the description logic ALBO and show 
that it provides a basis for decision procedures for this logic and 
numerous other description logics with full role negation.  ALBO is the 
extension of the description logic ALC with the Boolean role operators, 
inverse of roles, domain and range restriction operators and it includes 
full support for nominals (individuals).  ALBO is a very expressive 
description logic which subsumes Boolean modal logic and the 
two-variable fragment of first-order logic and reasoning in it is 
NExpTime-complete.  An important novelty is the use of a generic, 
unrestricted blocking rule as a replacement for standard loop checking 
mechanisms implemented in description logic systems.  An 
implementation of our approach exists in the MetTeL system.