not 100% filled out and CAN not 100% filled out
- speaking about actuality or possibility
Thank you for your patient answer. I thought that one adds activities and fills only 26 hours for each group, and the four-hours course is inculded in 26 hours. For "it might happen that 10a has free and 10b has a lesson. it is not simultaneously" and "But if the groups (classes) 10a and 10b have less then 26 hours per week, then the timetable of the student is not 100% filled" gave me impression that the adding is completed. Now suppose that the activities are so added that there remain four hours free. So one can cover these four hours with a four hours course. It follows that all thirty hours are filled. Suppose the activities are so added that there remain some hours free for one group. One may say a priori that the resulted timetable for this group cannot be filled out 100% although one does not know when a course shall with which teacher started.
In the generated timetable an activity appears with all its particularity (time, place, teacher, students). In this way a generated timetable is filled out. What you mean by "a filled out timetable" is not so filled out. You mean that if the activities are not added enough, one knows a priori the generated timetable cannot be filled out. You are speaking about possibility, rather than actuality. Imagine that if we have no help from program, we do fill a timetable with activity's name, teacher's name, and room's name. We do speak about a 100% filled out timetable. In this case we are speaking about actuality.
"These activities are scheduled simultaneously if the timetable is 100% filled." means
"These activities are necessarily scheduled simultaneously if every period of the timetable is filled with an or a part of activity". This can be misleading because one does not actually fill a timetable with a certain activity. Perhaps better: "These activities are necessarily scheduled simultaneously if activities are added enough so that no period of the timetable can be uncovered".