Part I Yingkang: Remembering Professor Yingkang Hu -- Remembrances -- On Some Properties of Moduli of Smoothness with JacobiWeights -- Part II Approximation Theory, Harmonic and Complex Analysis, Splines and Classical Fourier Theory -- Special Difference Operators and the Constants in the Classical Jackson-Type Theorems -- Comparison Theorems for Completely and Multiply Monotone Functions and Their Applications -- Concerning Exponential Bases on Multi-Rectangles of Rd -- Hankel Transforms of General Monotone Functions -- Univalence of a Certain Quartic Function -- Finding, Stabilizing, and Verifying Cycles of Nonlinear Dynamical Systems -- Finding Orbits of Functions Using Suffridge Polynomials -- The Sharp Remez-Type Inequality for Even Trigonometric Polynomials on the Period -- The Lebesgue Constants of Fourier Partial Sums -- Liouville–Weyl Derivatives of Double Trigonometric Series -- Inequalities in Approximation Theory Involving Fractional Smoothness in Lp, 0 < p < 1 -- On de Boor–Fix Type Functionals for Minimal Splines -- A Multidimensional Hardy–Littlewood Theorem -- The Spurious Side of DiagonalMultipoint Padé Approximants -- Spline Summability of Cardinal Sine Series and the Bernstein Class -- Integral Identities for Polyanalytic Functions -- Pointwise Behavior of Christoffel Function on Planar Convex Domains -- Towards Best Approximations for