Rad HAZU, Matematičke znanosti, Vol. 29 (2025), 221-229.

AN EMBEDDING OF THE CANTOR FAN INTO THE LELEK FAN

Iztok Banič, Goran Erceg and Judy Kennedy

Faculty of Science, University of Split, Rudera Boškovića 33, 21000 Split, Croatia
e-mail: goran.erceg@pmfst.hr

Department of Mathematics, Lamar University, 200 Lucas Building, P.O. Box 10047, Beaumont, Texas 77710 USA
e-mail: kennedy9905@gmail.com

Abstract.   The Lelek fan L is usually constructed as a subcontinuum of the Cantor fan in such a way that the set of the end-points of L is dense in L. It easily follows that the Lelek fan is embeddable into the Cantor fan. It is also a well-known fact that the Cantor fan is embeddable into the Lelek fan, but this is less obvious. When proving this, one usually uses the well-known result by Dijkstra and van Mill that the Cantor set is embeddable into the complete Erdős space, and the well-known fact by Kawamura, Oversteegen, and Tymchatyn that the set of end-points of the Lelek fan is homeomorphic to the complete Erdős space. Then, the subcontinuum of the Lelek fan that is induced by the embedded Cantor set into the set of end-points of the Lelek fan, is a Cantor fan.
    In our paper, we give an alternative straightforward embedding of a Cantor fan into the Lelek fan. We do not use the fact that the Cantor set is embeddable into the complete Erdős space and that it is homeomorphic to the set of end-points of the Lelek fan. Instead, we use our recent techniques of Mahavier products of closed relations to produce an embedding of the Cantor fan into the Lelek fan. Since the Cantor fan is universal for the family of all smooth fans, it follows that also the Lelek fan is universal for smooth fans.

2020 Mathematics Subject Classification.   37B02, 37B45, 54C60, 54F15, 54F17.

Key words and phrases.   Closed relations, Mahavier products, fans, Cantor fans, Lelek fans.

DOI: https://doi.org/10.21857/m8vqrt3lk9

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