COMP 3513 – Quiz #1
SOLUTION SHEET
1. Consider the DFD in Figure 6–20 shown below. List three errors (rule
violations) on this DFD.
Three major errors in Figure 6–20 are:
 Process 1.0 (P2) has only inputs, making it a “black hole”.
 Data flow DF5 should not move directly from source E1 to data store
DS1 without first going through a process.
 Data flow DF1 should not move directly from source E1 to sink E2
without first going through a process.
 Other peculiarities (such as Process 1.0 has label P2 and the data
store has only a label, not a number) are only that, not errors.
 DF6 is an inappropriate line crossing; it makes for a more confusing
diagram and does not have to be drawn in this way.
2 .Consider the three DFDs in Figure 6–21 shown below. List three errors (rule
violations) on these DFDs.
These diagrams show the decomposition of process P1 on the level-0 diagram.
Three particular logical errors in Figure 6–21 are:
 The data store DS1, not DS2, should be represented on the level-1
diagram.
 Data flow DF6 should not be on the level-1 diagram.
 Data flow DF3 should be an outflow on the level-1 diagram.
 Process P1.4.2 has no inputs and is thus a “miracle.”