Bibliography
Bacon, P.: Compact means in the plane. Proc. Amer. Math. Soc.22, 242–246 (1969).
Browder, W.: On torsion inH-spaces. Ann. of Math. (2)74, 24–51 (1961).
Crummer, A.: Topological means. Doctoral dissertation. University of Florida, 1971.
Eckmann, B.: Räume mit Mittelbildungen. Commentarii Math. Helvet.28, 329–340 (1954).
Eckmann, B. Ganea, T., Hilton, P.: Generalized means, from Studies in Mathematical Analysis and Related Topics, edited by Gilber et. al. Stanford Univ. Press 1962.
Scheffer, W.: Generalizations of the homotopy lemma for Alexander cohomology. Master's Thesis, University of Florida, 1971.
Sigmon, K.: Acyclicity of compact means. Michigan Math. J.16, 111–115 (1969).
Spanier, E.: Algebraic topology. New York: McGraw-Hill 1966.
Whitehead, J. H. C.: On the homotopy type of ANR's. Bull. Amer. Math. Soc.54, 1133–1145 (1948).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sigmon, K. Idempotent topological groupoids with non-empty center. Math Z 125, 70–78 (1972). https://doi.org/10.1007/BF01111115
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01111115