Q: Verify ‖·‖₁ is a norm on ℝ². Compute ‖(3,-4)‖₁, ‖(3,-4)‖₂, ‖(3,-4)‖∞. ‖(x,y)‖₁ = |x|+|y|: positive ✓, homogeneous ✓, triangle ✓: NORM! ‖(3,-4)‖₁ = 7. ‖(3,-4)‖₂ = 5. ‖(3,-4)‖∞ = 4. Different norms, same topology (finite dim!)! (Unit balls: diamond, circle, square!)