Chapter 1. Topology on Geometric Sequence Spaces.- Chapter 2. Composition Operators on Second Order Ces`aro Function Spaces.- Chapter 3. Generalized Deferred Statistical Convergence.- Chapter 4. Approximation By Generalized Lupas, -P ˇaltˇanea Operators.- Chapter 5. Zachary spaces Z p[R ] and separable Banach spaces.- Chapter 6. New generalization of the power summability methods for Dunkl generalization of Sz´asz operators via q-calculus.- Chapter 7. Approximation by generalized Sz´asz-Jakimovski-Leviatan type operators.- Chapter 8. On Approximation of Signals.- Chapter 9. Numerical Solution for nonlinear problems.- Chapter 10. Sz´asz-type operators involving q-Appell polynomials.- Chapter 11. Commutants of the infinite Hilbert operators.- Chapter 12. On complex uncertain sequences defined by Orlicz function.- Chapter 13. Ulam-Hyers stability of mixed type functional equation deriving from additive and quadratic mappings in intuitionistic random normed spaces.- Chapter 14. A Study On Q-Euler Difference Sequence Spaces.