# Is this formal logic explanation of the difference between "что-нибудь" and "что-то"? [closed]

In formal logic, there is the notion of a distinction between "free variables" and "bounded variables".

I found this distinction difficult to understand, until I thought of it this way: free variables are indeterminate things which can be expressed in Russian as что-нибудь, while bound variables are unspecified things which can be expressed in Russian as что-то.

Question: Is this explanation correct? Do Russians (who know about formal logic) think about the concepts of свободные и связанные переменные?

The concepts really did not make much sense to me until I thought about them this way. Also this might not be a question strictly about the Russian language or culture, in which case I apologize and would gladly learn about a better place to ask. (StackOverflow на русском?)

Related questions:
"Что–то" or "что–нибудь"

What's the difference between the two suffixes -то and -нибудь?

I am sorry, I won't consider the terms you suggested, but perhaps you can find some connection. Unfortunately, there are more variants что‐то, кое-что, что‐нибудь, что‐либо, which are hard to explain to foreigners.

1. Что‐то shows that the subject is unknown to both the speaker and the recipient.

Что‐то промелькнуло в воздухе.

1. Кое‐что means that the subject is partly known th the speaker and unknown to the recipient.

Я кое‐что помню об этом случае.

1. Что‐нибудь means "no matter what/ not important what "

Дай мне что‐нибудь поесть.

1. Что‐либо is very close to что‐нибудь, it has a more general meaning of "one of any taken subjects ".

попросить кого-нибудь (ask somebody, no matter whom ), попросить кого-либо (ask somebody, any unknown person ). The difference is subtle.

Back to your question: -то means "something unknown", whereas -нибудь means "no matter what"

"Что-то" is "something (as in unspecified)", "что-нибудь" ("что-либо") is "anything".

The "free" variables have their (approximate?) equivalent in "независимые переменные".