https://arxiv.org/abs/0903.2773
[0903.2773] Homotopy sphere representations for matroids
Abstract page for arXiv paper 0903.2773: Homotopy sphere representations for matroids
homotopy sphere09032773representationsmatroids
https://www.wolframalpha.com/input/?i=homotopy+3-sphere
homotopy 3-sphere - Wolfram|Alpha
3 spherehomotopywolframalpha