All three LOR from math professors while applying for CS program

Question

I am planning to apply to Master in CS programs in various top institutes. All 3 of my potential referees are from pure math background. Two of them work in Number theory and the other works in Representation/Algebraic Combinatorics. I have worked with CS professors too, but they were mostly reading projects. With two of the referees, I worked on a research project and other professor's class I have TAed and attended.

All three are very important for my applications. They reflect my TA qualities and my research qualities.

However, I am applying for master in CS because I am not sure if I want to pursue math or cs in PhD. I spent a lot of time in math research and I feel a masters in CS will help me see how research in CS looks like.

However, will taking LOR from 3 math professors affect the chances?

A few more details: I am doing a double major in math and CS( mainly theoretical CS). And I have taken graduate-level courses in both math and CS where I have received decent grades. And I have TA experience in both math and CS.

Answer 1

CS to Math and Math to CS is not an uncommon transition that students might choose to make between undergraduate and graduate schools. You are also majoring in CS, so you are certainly a suitable candidate. I will add that your own statement about why you want to study CS and not pure math will also be important here—try to bridge the two fields in a way that is meaningful to you, and how the program can help you further that.

Now to answer your question, I find that there are two possibilities:

1. If your school is at a comparable standing to the schools you are applying to, this should be fine for Master's programs, which generally accept a diverse pool of students—although one might still wonder why you don't have any letters from CS professors. I am of the opinion that it is better to address it than let it linger. You don't need to explain too much, but just explaining that you worked closely with (Math professors) Drs. A, B and C on such-and-such projects is sufficient.

2. If your school is not at a comparable standing to the schools you are applying to, I would consider speaking with at least one of the CS professors (perhaps the theory one), but I would also be applying to less ambitious safety schools in addition.

PS. Be aware that you may not get a TA position at the time of admission. These positions are competitive, and in my experience, they are offered to Master's students only when there are vacancies after all the PhD students have been assigned. In general, they may not care all that much about your undergraduate TA experience, but it doesn't hurt.

Answer 2

I assume you are in the US.

First, TA positions are scarce resources, which are usually reserved to Ph.D. students if the university has a Ph.D. program.

If you are interested in a Ph.D. apply for a Ph.D. admission if you are competitive. Most people who enter doctoral studies are not 100% sure that they want to get a Ph.D. and a number finish after an M.S. It seems to me that you are trying to get letters for a Ph.D. admission where creativity and the ability to work semi-independently become important criteria.

Most M.S. programs in the US are strictly "commercial": they give you something of value and they expect money from you. Scholarships are rare. Programs other than the very elite programs will only evaluate whether there is a good chance for you to finish studies. There might be exceptions for the social good, e.g. to diversify the CS work force. Good letters from Mathematics professors are good enough to determine whether you will successful. Good grades from a decent school are equally important.