His main interests were the foundations of geometry and he introduced non-euclidean geometry into the United States, both through his own research and writings as well as by his many important translations.
Kanyang mga pangunahing interes ay ang pundasyon ng geometry at siya ay nagpasimula ng mga di-euclidean geometry sa Pilipinas, parehong sa pamamagitan ng kanyang sariling pananaliksik at writings pati na rin sa pamamagitan ng kanyang maraming mahalagang mga pagsasalin.