 		;;
 		;; evaluable functors:
 		;;
+		("\\(abs\\|ceiling\\|flo\\(?:at\\(?:_\\(?:\\(?:fractional\\|integer\\)_part\\)\\)?\\|or\\)\\|mod\\|r\\(?:em\\|ound\\)\\|sign\\|truncate\\)\\([(]\\)" 1 'logtalk-built-in-predicate-face)
 		("//\\|mod\\|rem\\|[*+/-]" . 'logtalk-operator-face)
-		("\\(abs\\|ceiling\\|flo\\(?:at\\(?:_\\(?:\\(?:fractional\\|integer\\)_part\\)\\)?\\|or\\)\\|mod\\|r\\(?:em\\|ound\\)\\|sign\\|truncate\\)\\([(]\\)" 1 'logtalk-built-in-predicate-face)
 		;;
 		;; other arithemtic functors:
 		;;


(make-face 'logtalk-operator-face)
(set-face-foreground 'logtalk-operator-face "blue")
(set-face-bold-p 'logtalk-operator-face t)

(make-face 'logtalk-string-face)
(set-face-foreground 'logtalk-string-face "brown")

		;; term creation and decomposition:
		;;
		("\\(arg\\|copy_term\\|functor\\)\\([(]\\)" 1 'logtalk-built-in-predicate-face)
		("=\\.\\." . 'logtalk-operator-face)
		;;
		;; arithemtic evaluation:
		;;
