# Subset notation with the bar crossed

Reading the book 'An Introduction To Continuous Optimization', I ran across the $\subseteq$ notation, but with the little bar crossed over with a small $45^o$ dash - only the bar, not the whole symbol. I don't know how to do it in latex but I hope you get the idea.

What does this mean?

Do you mean $\subsetneq$?
It's used by some to denote a proper subset and is used instead of $\subset$.
• Yep, that's the one. Is it equivalent with $\subset$? – Benjamin Lindqvist Oct 30 '14 at 9:47
• @BenjaminLindqvist Yes, although sometimes when $\subsetneq$ is used $\subset$ will be used for standard inclusion (proper or not), so be careful. I have never seen $\subsetneq$ used to refer to anything other than proper inclusion however. – Benjamin Oct 30 '14 at 9:49
• @BenjaminLindqvist Really? It might be using $\subsetneq$ for emphasis. – Benjamin Oct 30 '14 at 9:54