# Do we really want (discrete-mathematics) $\to$ (combinatorics) synonym?

I have noticed in the list of tag synonyms that a synonym $\to$ has been suggested. Currently it awaits votes from users.

I am not sure this is a reasonable tag synonym. But I definitely think that such a synonym should not be created without discussing it on meta beforehand - this is a synonym which would influence a very big number of questions.

EDIT: In the meantime, the synonym suggestion has been downvoted to $-2$ and hence removed. (Probably it was noticed partly thanks to this meta post.)

• I feel like it's a good idea to alter the person whose suggestion this was: @Leila Hatami – Stella Biderman Apr 4 '17 at 17:37
• @StellaBiderman That won't notify Leila since they did not comment on this post. See meta.stackexchange.com/questions/43019/… – Mike Earnest Apr 4 '17 at 18:44
• @MikeEarnest oh interesting. Thanks for the information. – Stella Biderman Apr 4 '17 at 18:44
• Also, it's probably a better idea to alert Leila than to alter her. – Gerry Myerson Apr 5 '17 at 7:02
• @StellaBiderman I have pinged Leila Hatami in chat. To my best knowledge of chat and notifications in chat, she should get some notification about this. – Martin Sleziak Apr 5 '17 at 9:28
• @MartinSleziak Thank you for notifying me. The suggestion has been closed and there is post with 19 votes against it! I know that this two concepts are far away but I suggest it for more organization. I thought that removing combinatorics and merge it to discrete math could be useful.... – MR_BD Apr 5 '17 at 10:56

I am against this synonym. Although many discrete math problems are also combinatorics problems, and depending on your definition it might be that all combinatorics problems are discrete math problems, they don't mean the same thing. There are many many discrete mathematics problems that are not combinatorics problems, such as problems in elementary number theory, set theory, and graph theory.

If people are using the tags together at a high enough rate as to make them look like synonyms (I don't have information one way or the other) that should be remedied by making the correct tag use clearer, not by making the tags synonyms. There's definitely a lot of questions that get asked that are discrete math and not combinatorics.

• I agree; combinatorics is at the very least only a subset of discrete-mathematics. – J. M. is a poor mathematician Apr 4 '17 at 13:55
• Agreed. "Discrete mathematics" is used to distinguish it from "continuous mathematics". Similarly, we do not want a synonym (continuous mathematics) -> (calculus). – GEdgar Apr 4 '17 at 14:26
• Hmm, I always thought graph theory was combinatorics. But otherwise, I agree. – Thomas Andrews Apr 13 '17 at 16:40
• @ThomasAndrews some of it is, but questions about, e.g. DFS aren't combinatorics questions but are graph theory questions. Graph theory is roughly divided into combinatorial and algorithmic IMO. – Stella Biderman Apr 13 '17 at 17:08

Reject

I took discrete mathematics in College (well actually the computer science version). There were 3 main things I was told were actually the same in both sections: Boolean algebra, predicate logic, and set theory. Then we went on to do programming stuff whereas the math version examined types of proofs (in general and from what I heard involving basic algebra and calculus). The only time combinatorics ever came up was when the professor mentioned factorial as the prime example of a recursive function. Considering this was the only mention of combinatorics, discrete math cannot possibly be combinatorics. Surely there would've been more in the class if that were the case!

So I'm gonna guess that whoever did this did it out of error. They probably intended to make combinatorics a subset of discrete math and not the other way around. I'd just disregard the request. On another note, perhaps explaining that the tag system is NOT tree like would be good. Cause I can see the advantage of making one a sub tag of the other.

• Of course the computer science version -- because that's what "discrete mathematics" is: a common codeword in CS programs for "the selection of mathematics we think CS majors need to learn". It doesn't really count as a discipline within mathematics itself, and actual mathematics programs don't have any "discrete mathematics" course. – Henning Makholm Apr 5 '17 at 11:47
• @Henning Makholm: My school has a math class called "Discrete Math" and a CS course called "Discrete Math and Probability". Barring some exceptions, if you majored in math, the CS class would not count toward your major and vice versa. Seemed (although I cant say for sure since I didn't take both) to me like discrete math only was mostly used as a pedagogy tool for introducing proof methods. The CS course was more like you said. – Dair Apr 6 '17 at 3:28
• @HenningMakholm actually, as stated in my answer there are in fact two versions of the course. One is called "Discrete Math Structures" which is for Computer Science majors and the other is "Discrete Math" which is for Math majors. Both count as credit for the other (I should know as I am a double major in both) and they are virtually the same class. I should note that both are required in the two degrees. The only differences between the two are the things I mentioned in my post. Towards the second half of the course, we switched gears and did more recursion-based programming concepts.... – The Great Duck Apr 6 '17 at 4:55
• (continued) ...whereas the mathematics version studied various examples of actual proof found in mathematics. I heard from other students that they seemed to focus around simple things in calculus and algebra. So, regardless of it being a discipline there is certainly a pretense for it being studied as a subject. Besides, we are not here to discuss the viability of discrete math.Rather, we are discussing whether it is equivalent to probability and I say that it is not as not only does a class baring its name not at all cover it, but probability also involves calculus and 'continuous' math! – The Great Duck Apr 6 '17 at 4:59
• Who said anything about probability? There was a proposal to synonymize "discrete math" to combinatorics, but nothing about probability. – Henning Makholm Apr 6 '17 at 6:53
• @HenningMakholm Minor slip of the tongue that's all. I just mixed up the terms probability and combinatrics (they tend to go together pretty closely in the eyes of statistics). My point still stands though. Neither class involved combinatrics. Unless you call set theory combinatrics. However, then that would warrant a completely different proposal. Combinatrics can probably still involve continuous functons and calculus anyways. I don't know of the actual but I've heard such a thing exists somehwere in more advanced statistical analysis. – The Great Duck Apr 6 '17 at 18:34