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Lattices associated with partial linear maps of finite vector spaces. (English) Zbl 1324.51005

Let \(F_q\) be a finite field with \(q\) elements and let \(F_q^n\) be the \(n\)-dimensional vector space over \(F_q\). An \(\ell\)-partial linear map of \(F_q^n\) is \((V, f)\) where \(V\) is an \(\ell\)-dimensional subspace of \(F_q^n\) and \(f: V \to F_q^n\) is a linear map. The authors consider the partially ordered sets of partial linear maps, one ordered by inclusion and the other ordered by reverse inclusion. They prove these posets are in fact finite lattices and for \(n \geq 2\) neither is a geometric lattice. The Möbius functions are given and characteristic polynomials are computed.

MSC:

51D25 Lattices of subspaces and geometric closure systems
05B35 Combinatorial aspects of matroids and geometric lattices
20G40 Linear algebraic groups over finite fields