Unfortunately Ruby is <i>not</i> wrong. Ruby is simply being strictly correct from a logic point of view, where &#60; is R^2 -&#62; {T, F}, as opposed to being strictly correct from a math-notation point of view, where &#60; is treated syncategorematically. Neither is correct, sans qualification; given that Ruby is not aimed at mathematicians, it's not unsurprising to find that it's not going to go through the extra parsing effort to use math notation.