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Video in reference: https://youtu.be/dUwN6GI-0EQ after 4:05

In a Cambridge (model) interview, someone was asked to sketch a graph of sin(x)/x. The intention was clearly that they were not to have seen this function before. When watching, I immediately recognised this as sinc(x) (a function sometimes used in electrical engineering). They were then told not to evaluate this function at 0 because it's difficult, however I knew how this could be done. If I was in this position, would it be acceptable to pretend like I could derive everything I knew about this function already to impress the interviewer, or important to say that I have already seen the function before.

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    Generally best to tell the truth, as a baseline... (for most of us...) – paul garrett Feb 6 at 21:44
  • Pretense is often caught. And what if you get it wrong anyway? – Buffy Feb 6 at 22:03
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    Also, how is it clear to you that they were not expected to have seen that function before? It is one of the iconic examples... Indeed, when I design exams or tests of any sort, I don't seriously expect people to solve serious puzzles in real time while I'm staring at them, but, rather, hope that they recall having seen the things before. So I'm entirely happiest to hear people respond "oh, yes, I've done this before. It goes as follows..." Perfect. – paul garrett Feb 6 at 22:21
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    You have seen sin x, so sin x / x is really simple without having seen it. Taylor formula is 1 - x^2/6 + x^4/5! etc. so it starts with y = 1 going down to 2/pi at pi/2, going down to 0 at pi, and then it looks like sin except it gets flatter and flatter, enveloped by +/- 1/x. – gnasher729 Feb 6 at 22:38
  • They were then told not to evaluate this function at 0 because it's difficult --- (mathematical wording nitpick) Well, unless you say more about the function than simply sin(x)/x, it can't be evaluated at x = 0 because it's not defined at x = 0. Of course, it has a removable singularity at x = 0 (i.e. limit exists at x = 0), so there's an obvious (to the presenter, at least) continuous extension to x = 0, and that continuous extension is defined at x = 0. – Dave L Renfro Feb 7 at 7:25
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I really don't think the interviewer cares one way or another whether you've seen the problem before. She just wants to know if you can solve it, and to hear how you go about it.

In the video, she does say "the function that I'm going to write down, you've probably not seen before"; but I interpret that as just a way to reassure the student that the problem should be possible to solve whether she has seen the function before or not. It's so the student doesn't panic or get stuck trying to remember the function, rather than actually trying to solve the problem.

So I don't think there is any point in either pretending the problem is new to you, or in announcing that it's familiar. Neither will significantly help or hurt you in itself. If you know how to solve the problem, solve it and move on.

On the other hand, it probably wouldn't be helpful to just draw the graph from memory and say "here it is, done". The interviewer is almost certainly more interested in having you demonstrate that you understand the concepts and methods used to solve the problem, than in seeing if you know the solution. So you would be wise to work through the problem methodically, explaining what you are doing and how you know to do it.

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NO. What you are describing is dishonest behavior. It is absolutely, categorically, not acceptable to behave dishonestly in an academic interview.

And if you think you can get away with it, I think you’re severely underestimating how easy it would be for the interviewer to notice your pretense.

Don’t do it. It’s a terrible idea.

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This happened in my Cambridge interview. I think you are presupposing that it is necessary to either come clean or deceive. I don't think it would play out like that unless they explicitly ask "have you seen this before?" (which in my experience they wouldn't bother asking). I would just answer all the questions you can to the best of your ability. They aren't going to say "You've seen it before and didn't say so, so you cheated".

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