System Modelling 2019/2 -- Theoretical Questions 1
Example theoretical questions for practising for the 2nd mid-term exam in System Modelling. (In the mid-term exam, you get +1/4 point for each correct answer, -1/4 point for each incorrect ones, and 0 point for each question left out. You have to reach 50% of the possible points in this system. The Google Form is not able to implement this points system.)
1. An infinite loop (livelock) …
1/a … can also occur in case of a well-structured process model. *
1 point
1/b … cannot occur, if the process model is fully specified. *
1 point
1/c … means that the system cannot leave a given set of states, and cannot show any input or output activities. *
1 point
1/d … means that the system cannot leave a given part of the state space (e.g. a loop), but it can change its state inside of that part. *
1 point
2. Modelling tools …
2/a … can show different parts of a model with different concrete syntaxes. *
1 point
2/b … always work with a graphical concrete syntaxes, as only code generators and programming languages have textual syntaxes. *
1 point
2/c … differ from code generators in the sense, that modelling tools never work with concrete syntaxes, while code generators work with graphical concrete syntaxes. *
1 point
2/d … can examine structural correctness through statical analysis of the given abstract syntax, even during editing of the model. *
1 point
3. Runtime monitors …
3/a … only consider outputs of the system. *
1 point
3/b … check input and output invariants during runtime. *
1 point
3/c … can substitute testing, as they can prevent faulty operation during runtime. *
1 point
4. Test coverage …
4/a … is the measure of the correspondence of the expected and experienced output. *
1 point
4/b … is a value between 0 and 1. *
1 point
4/c … can be increased through new test cases. *
1 point
4/d … having a value of 1 means that there are surely no errors in the model/code. *
1 point
5. Model checking …
5/a … is the random examination of a model for some inputs. *
1 point
5/b … mathematically proves the correctness of a model. *
1 point
5/c … requires less computational effort than running a test suite, as the model does not have to be executed. *
1 point
5/d … can give an example, if a requirement is not met in a model. *
1 point
6. The visitation number of an elementary activity in a process …
6/a … is the ratio between the throughput and the maximum throughput of the activity. *
1 point
6/b … is the ratio between the throughput of the activity and of the whole process. *
1 point
6/c … is less than or equal to the maximum throughput. *
1 point
6/d … is equal to the arrival rate when the system is in balance. *
1 point
7. The maximum throughput of a process composed of two elementary activites P and Q with (respectively) XP and XQ maximum throughputs, and of any control structures, is …
7/a … min(XP, XQ), if P and Q are the two branches of a fork-join block. *
1 point
7/b … (XP + XQ), if P and Q are in a free choice relationship. *
1 point
7/c … is always the same as the maximum throughput of the bottleneck (P or Q). *
1 point
7/d … is always min(XP, XQ). *
1 point
8. We examine the shoe size, eye colour and degree level (BSc, MSc, PhD) of students.
8/a Shoe size is an ordered categorical variable. *
1 point
8/c Degree level is an ordered categorical variable. *
1 point
8/d Degree level is a numerical variable. *
1 point
9. We examine the shoe size and the total exxam score of the two System Modelling mid-terms of students.
9/a If the two variables represented on a parallel coordinate diagram result in parallel polylines, then everyone achieved the same score as his/her shoe size. *
1 point
9/b If the two variables represented on a parallel coordinate diagram result in parallel polylines, then the shoe size is a linear function of the total exam score. *
1 point
9/c If the shoe size and the total exam score represented on histograms result in two identical histograms, then everyone has achieved the same score as his/her shoe size. *
1 point
10. The median …
10/b … is always greater than the mode and less than the average. *
1 point
10/c … appears explicitely on a boxplot. *
1 point
10/d … is only defined for an odd number of data elements. *
1 point