# File ai/csp/constraint.rb, line 100
        def propagate(variable, level)
            value = variable.value
            uninstantiated_variables.each { |v|
                value_index = v.domain.index(value)
                if value_index.nil? or v.pruned?(level,value_index)
                    next
                end
                v.prune(level,value_index)
                return false if v.domain_empty?(level)
            }
            true
        end