              return "The text states the second-order convexity condition: if \\( f : \\mathbb{R}^d \\to \\mathbb{R} \\) is twice continuously differentiable, then \\( f \\) is convex if and only if \\( \\nabla^2 f(x) \\succeq 0 \\), for all \\( x \\in \\mathbb{R}^d \\).";
                    case 2:
                        return "The text states that 'When \\( f \\) is strictly convex, the global minimizer is unique (if it exists).' Convex functions need not be differentiable, as illustrated by the examp