This is a question of notation. I have seen in many articles that people often denote $+\infty$ when talking about 'positive infinity' of the real numbers. Is that a convention, or it can be written as anyone pleases? I never liked the notation $+\infty$ because it seemed that the $+$ sign is redundant. In my opinion there is no confusion if someone writes $\infty$ for the positive infinity and $-\infty$ when talking about the negative infinity.
Still, the fact that I've seen the $+\infty$ notation in almost every article I've read in a while made me ask this question.
Is the $+$ in the notation $+\infty$ necessary? Do $\infty$ and $+\infty$ mean the same thing? (of course I'm talking about the real line here)