# Why do we denote binary relation in search problem by $R$?

It is interesting for me to know why do we denote binary relation of the search problem by $R$. Is it only because of the word Relation or something else takes place in the denotation?

• That sounds like a plausible guess. But it's unclear what you're asking about: what is "the" search problem, which binary relation is denoted by $R$, and who is "we" who denote it that way? Maybe if you're lucky someone reading this has just read the same book as you or attended the same lecture, but the rest of us don't have that context. – David K Jan 20 '17 at 21:22
• If not all of you have that context , then it is not an important matter. Thank you for attention. – oobarbazanoo Jan 21 '17 at 9:29
• The fact that we aren't all reading the same book at the same time doesn't make your concerns unimportant. Sometimes a notation will be used a little differently for a particular topic or by a particular writer, that's why I asked. But the letter $R$ is often used as a kind of placeholder relation symbol, and thinking of it as standing for the word "relation" often works for me. It sounds like that is probably the kind of thing you are looking at now. – David K Jan 21 '17 at 10:29
• Yes. In my matter it is very appropriate to consider R to be the denotation of relation. – oobarbazanoo Jan 21 '17 at 10:53