Signal spaces: Inner product, infinite-length signals, and completeness

This lecture covers signal spaces, including finite-length and periodic signals living in CN, inner product for signals defined for finite-length vectors, the concept of infinite-length signals and the requirement for sequences to be square-summable, the distinction between well-behaved infinite-length signals in l₂(Z) and incomplete spaces like the set of rational numbers, and the definition of Hilbert Space as a vector space with an inner product and completeness.