Discussiones Mathematicae Graph Theory 33(2) (2013) 277-288
doi: 10.7151/dmgt.1662

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Exact expectation and variance of minimal basis of random matroids

Wojciech Kordecki

University of Business in Wrocław
Department of Management
ul. Ostrowskiego 22, 53-238 Wrocław, Poland

Anna Łyczkowska-Hanćkowiak

Poznań University of Economics
Faculty of Informatics and Electronic Economy
Department of Operations Research
al. Niepodległości 10, 61-875 Poznań, Poland


We formulate and prove a formula to compute the expected value of the minimal random basis of an arbitrary finite matroid whose elements are assigned weights which are independent and uniformly distributed on the interval [0,1]. This method yields an exact formula in terms of the Tutte polynomial. We give a simple formula to find the minimal random basis of the projective geometry PG(r-1,q)

Keywords: minimal basis, q-analog, finite projective geometry, Tutte polynomial

2010 Mathematics Subject Classification: 05B35, 05C80.


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Received 2 March 2011
Revised 3 October 2011
Accepted 5 March 2012