3 ms·> the ℤ⁺²-projective vector space Semi-erratum: that's "(ℤ⁺)²" (aka "ℤ⁺×ℤ⁺"), not "ℤ⁽⁺²⁾".by a1369209993 3y ago> the ℤ⁺²-projective vector space Semi-erratum: that's "(ℤ⁺)²" (aka "ℤ⁺×ℤ⁺"), not "ℤ⁽⁺²⁾".