$title example of set membership logical condition

set 
    days /Sun, Mon, Tue, Wed, Thu, Fri, Sat/
    weekdays /Mon, Tue, Wed, Thu, Fri/;

parameter 
	workdone(days)
	lunchtime(days)
;

workdone(days) = 8$weekdays(days) + 4$(not weekdays(days)) 
	+ 2$sameas(days,"Sat");

display workdone;