[gridspy]

Putting "The sky is black" as a title seems incorrect to me, even though the statement "The sky is black on the Moon" is true.

[catnaroek]

+, × (or ·), 0 and 1 are standard notation in algebra for an arbitrary ring's addition, multiplication, additive identity and multiplicative identity. In that context, 1 + 1 = 0 isn't automatically false. It's just a statement that holds in some rings (e.g., F_2), but not in others (e.g., Z).