We investigate the maximum number of distinct palindromic sub-words in a two-dimensional finite word. We give tight bounds for the maximum number of distinct palindromic sub-words in two-row periodic/aperiodic words. Using this, we give upper bounds for the number of distinct palindromic sub-words for 2D words of larger sizes. Lastly, we propose a better bound for any finite 2D word.

中文翻译：

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二维回文的枚举

我们调查二维有限字的不同回文子字的最大数量。我们为两行周期性/非周期性词中不同回文子词的最大数量给出了严格的界限。利用这一点，我们给出的不同的回文子字对于较大规模的2D字的数目的上限。最后，我们提出了一个更好开往任何有限的2D字。