Questions pertaining to logical constructs

learn more… | top users | synonyms

16
votes
7answers
13k views

Does “either A or B ” preclude “both A and B”?

In mathematics, "A or B" includes "A and B". Does "either" mean "A or B but not (A and B)" or does it include the possibility of "A and B"? The context might be mathematics, formal logic or ordinary ...
8
votes
5answers
74k views

“Centered on” or “centered around”

I have often heard presenters talking about something centered around another thing, but it seems a bit illogical and hence improper to talk like this. Am I right about this?
6
votes
6answers
899 views

The word 'not' often doesn't mean total negation in mathematical sense?

Consider the following conversations: X1: I paid $10 for that hamburger. Y1: That's not cheap! X2: I pay $1 for broadband Internet access. Y2: That's cheap! X3: I paid $1 for a hot ...
4
votes
2answers
330 views

Is it true that

Is the following sentence grammatically incorrect? Is it true that 1+1=2 ? I know it is easier to say: Is 1+1=2 true?