Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We present new quantum lower bounds and upper bounds for several computational geometry problems. The bounds presented here improve on currently known results in a number of ways. We give asymptotically optimal bounds for one of the problems considered, and we provide, up to logarithmic factors, optimal bounds for a number of other problems and, in particular, we settle an open problem of Bahadur et al. Some of these new bounds are obtained using a general algorithm for finding a minimum pair over a given arbitrary order relation.75935947Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [140756/2004-3, 304363/2008-1]FAPESP [02/07473-7]