MODEL:
SETS:
    DAYS / MON TUE WED THU FRI SAT SUN/:
     NEEDS, START, ONDUTY;
 ENDSETS

 [OBJECTIVE] MIN = @SUM( DAYS( I): START( I));

 @FOR( DAYS( TODAY):

 ! Calculate number on duty;
    ONDUTY( TODAY) = 
     @SUM( DAYS( D)| D #LE# 5:
      START( @WRAP( TODAY - D + 1, @SIZE( DAYS))));

 ! Enforce staffing requirement;
    ONDUTY( TODAY) >= NEEDS( TODAY);

    @GIN( START);
 );

 DATA:
    NEEDS =  @POINTER( 1);
    @POINTER( 2) = START;
    @POINTER( 3) = ONDUTY;
    @POINTER( 4) = OBJECTIVE;
    @POINTER( 5) = @STATUS();
 ENDDATA
END