Q: Does y' = √|y|, y(0) = 0 have a unique solution? f(y) = √|y|: NOT Lipschitz at 0 (derivative ∞!). Solutions: y = 0 AND y = x²/4 (x≥0), 0 else... check: y' = x/2, √|y| = |x|/2: for x≥0 ✓! Also y = 0! TWO solutions: NON-UNIQUENESS! (Picard fails: no Lipschitz!)