## Correct mathematical symbol to represent "subtype"

If this question doesn't make sense, it's probably because I might be confused with the term subtype.

What is the correct mathematical symbol for subtype ?
if B is a subtype of A, which do I write:

1. B â‰¤ A
2. B <: A

Thanks.

## Comment viewing options

### Mostly <:

I think <: is most common, but you'll probably see some variation. It also depends a bit on the context. Sometimes one might want to consider the subtype relation as just another partial order, in which case it might be desirable to use another symbol.

### Proper or improper subtype?

I've also seen the subset operator (⊂ for the proper case, ⊆ for when equality is included) used.

### â‰¤ and âŠ‚ are already defined

I would think that <: would be the best representation since the above mentioned ones are already defined to have other meanings in mathematics. I haven't seen <: and :> used in any context (other than pointy mouthed smileys :) that it would make the most sense and create the least confusion over the other suggestions.