An RNA secondary structure is designable if there is an RNA sequence which can attain its maximum number of base pairs only by adopting that structure. The combinatorial RNA design problem, introduced by Hale\v{s} et al. in 2016, is to determine whether or not a given RNA secondary structure is designable. Hale\v{s} et al. identified certain classes of designable and non-designable secondary structures by reference to their corresponding rooted trees. We introduce an infinite class of rooted trees containing unpaired nucleotides at the greatest depth, and prove constructively that their corresponding secondary structures are designable. This complements previous results for the combinatorial RNA design problem.

中文翻译：

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对应于可设计的 RNA 二级结构的无限类不饱和根树

如果存在仅通过采用该结构就可以达到其最大碱基对数的 RNA 序列，则该 RNA 二级结构是可设计的。Hale\v{s} 等人提出的组合 RNA 设计问题。在 2016 年，是确定给定的 RNA 二级结构是否可设计。Hale\v{s} 等。通过参考它们相应的有根树，确定了某些类别的可设计和不可设计的二级结构。我们在最大深度引入了无限类包含未配对核苷酸的有根树，并建设性地证明它们相应的二级结构是可设计的。这补充了先前关于组合 RNA 设计问题的结果。