The table below illustrates the availability of four interviewers (1, 2, 3, 4) at four time slots (1, 2, 3, 4). A 1 in the table indicates that the corresponding interviewer is available at the corresponding time slot.

For example, the first interviewer, 1, is available at time slots 1 and 2.

Each interviewer may only take one interview and all four slots should follow sequentially, like 1 → 2 → 3 → 4.

What are all possible sequences of interviewers? Can this be generalised?

|  | 1 | 2 | 3 | 4 |
| --- | --- | --- | --- | --- |
| **1** | 1 | 1 | 1 | 1 |
| **2** | 1 | 1 | 0 | 0 |
| **3** | 0 | 1 | 1 | 0 |
| **4** | 0 | 1 | 1 | 1 |