Some Results on Pseudo-Collar Structures on High-Dimensional Manifolds

In this paper, we recall Quillen's plus construction for high-dimensional smooth manifolds and the solution to the group extension problem. We then develop a geometric procedure due for producing a "reverse" to the plus construction, a one-sided s-cobordism called a semi-s-cobordism, when the total group of the group extension is a semi-direct product. We then use this reverse to the plus construction to produce uncountably many different one-ended manifolds called pseudo-collars, which are stackings of semi-s- cobordisms. We finally display a technique for producing "nice" one-ended open manifolds which satisfy two of the necessary and suffcient conditions for being pseudo-collarable but not the third.