Progressive transmission represents a viable solution to the challenges presented by the transmission of large vector data sets over the Internet. Previous implementations have considered progressive transmission as the reverse of map generalization. In an adaptive or selective progressive transmission strategy, the order of transmission can vary between clients and generally will not equal the reverse of the corresponding generalization. In this context, we propose that generalization can only represent a pre-processing step to a distinct selective progressive transmission process. One of the greatest challenges in implementation of such an approach is determining topological equivalence with the original map. We propose this problem may be represented in the form of three challenges. We perform a formal mathematical analysis of solutions to these challenges and present a corresponding implementation.