Mathematical Sciences: Low Dimensional Topology

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8901412 Freedman The fundamental group restrictions presently required on the basic tools of 4-dimensional topology will be further explored. An effort will be made to evaluate -- zero or non-zero -- previously defined obstructions to the unfettered application of these tools. Towers of two-fold covers are to be employed as a useful way of organizing the secondary information whose efficient handling is a necessity for any successful outcome. The investigator is also alert to the contrary possibility that the obstruction vanishes, and the present approach is designed to pursue both possibilities together.