Bounds on the k-dimension of Products of Special Posets |
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Authors: | Michael Baym Douglas B West |
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Institution: | 1. Systems Biology Department, Harvard Medical School, Cambridge, MA, USA 2. Mathematics Department, Massachusetts Institute of Technology, Cambridge, MA, USA 3. Mathematics Department, Zhejiang Normal University, Jinhua, China 4. Mathematics Department, University of Illinois, Urbana, IL, 61801, USA
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Abstract: | Trotter conjectured that $\dim\, P\times Q\ge \dim P+\dim Q-2$ for all posets P and Q. To shed light on this, we study the k-dimension of products of finite orders. For k?∈?o(ln n), the value $2{\dim_k}(P)-{\dim_k}(P\times P)$ is unbounded when P is an n-element antichain, and $2{\dim_2}(mP)-{\dim_2}(mP\times mP)$ is unbounded when P is a fixed poset with unique maximum and minimum. For products of the “standard” orders S m and S n of dimensions m and n, $\dim_k(S_m\times S_n)=m+n-\min\{2,k-2\}$ . For higher-order products of “standard” orders, ${\dim_2}(\prod_{i=1}^t S_{n_i}) = \sum n_i$ if each n i ?≥?t. |
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