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Comment by nf05papsjfVbc | Hacker News Reader

"pretend you don't have solutions" is not a realistic approach. The strength of people's conviction to this will probably fall on a bell curve and few can resist the temptation when the problems get really tough. Accounting for how humans are, I do not see how one can easily say "Having solutions is strictly better". I can easily think of cases where it is indeed better to have solutions but to say "strictly" requires a bit more diligence.

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Don’t rob the self-learner that doesn’t have access to TAs, fellow students, and professors the ability to check their work, just because someone else doesn’t have the discipline to not abuse it.

Textbook solutions are good for those that aren’t in school, aren’t in formal programs and have no other way of receiving feedback.

The “you should know if you’re right” mentality doesn’t necessarily fit a person that’s been working for 10-years and has been out of the academic mindset. One that is a beginner and could easily fool themselves into thinking they have a correct answer.

It doesn’t allow for correction of false thinking. Anyone can think their proof is correct. But fewer beginners can properly recognize when they are wrong.

This sort of mentality is a bit elitist and gate keeping.

I had a girlfriend who was doing her PhD in Physics. I remember one night she and her classmates spent all night working on a problem, that was essentially unsolvable. The next day they go to class and all of them made their best attempt, but no one could complete it. The problem? The professor accidentally used the wrong metric on one of the numbers meaning that they couldn't do the steps to what should have been an easy solution. Now they noticed this, they are a smart group of people, but that's not what the problem was, so they spent hours and hours trying to solve what he gave them without any hope of actually doing it.

In the end, he was like "Oh my bad," and corrected his mistake. The point of the story is that they were able to essentially ask him for the solution and they were able to check what they'd done, and in the end he made the mistake. In situations like this, he should provide the answer if nothing else to show that he didn't make a mistake in the problem set. People are fallible, no matter how brilliant you are.

That professor probably had produced the answer already, using the metric he had initially intended. Having a set of answers doesn't mean you didn't make a mistake in the questions.

But it does clue you into whether the professor used a different set of assumptions than you did.

Presumably you wouldn't see the answers until after you spent all night on the assignment.

I had a similar thing happen in high school physics. We were were suppose to figure out where and when a projectile was going to land. The only problem was that it was never going to land—-the initial velocity was too high.

In retrospect I think it was a great lesson for my future career as a data engineer. Doesn’t matter what the source is, any datum can be just plain wrong.

> The only problem was that it was never going to land—-the initial velocity was too high.

As in, it escaped the gravitational field?

Yep.

There's a story of a prof injecting one error into every test.

I had a industrial engineering teacher that did something similar. Every team had a (fake money) budget for each project and bought materials from him (sole source). He'd randomly cut corners, to keep everyone on their toes. Good lesson for the real world.

On the other hand, struggling all night to solve an un-solvable problem is a valuable learning experience, too. In the real world we struggle all the time with problems that don't have solutions.

I took a quick look through the first set of exercises and a lot of the problems are open-ended and don't have specific answers. Seeing a different answer than yours doesn't tell you much about whether your answer is correct.

Even if you do have a similar proof to the one in the answer key, that doesn't mean your proof is correct. Correctness can often hinge on very subtle distinctions. You really need a TA or instructor to read your proof if you want meaningful feedback.

Presumably nothing's stopping you from putting a book of solutions and posting them online. It seems like a much easier task than writing this book, with all its problem sets, and then posting it online for free for the world to read.

As I've said elsewhere, I'm looking out for my own students first.

One of my colleagues suggested setting up a "club" on PerusAll (https://app.perusall.com/welcome) or something similar that would allow people to discuss to book and/or work through problems collectively. (They have a club for CLRS, for example.) Right now all their "clubs" are restricted to books with Reputable Publishers (ptui), so they might need some persuasion.

It might be an elitist and gate keeping mentality but I have to say that calling providing a free resource to someone, but not tailoring it to fit their exact situation, "robbing" is a very entitled one.

It is absolutely a realistic approach, what are you talking about? Is it also not a realistic approach to eat your vegetables or perform routine exercise like walking around the block?

Without solutions at the back of the book, self-directed learners can't verify their own work. Don't cut out the less privileged learners from bettering themselves just because you have no concept of discipline.

Well. It has worked really well for me and obviously a bunch of other engineers as a number of our books had solutions at the end of each chapter.

As long as cheats are only available for ungraded homework/self assessement tests cheaters are only going to cheat themselves.

I completely agree.

yes, exactly.

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