一句话：定义正则/一阶列表函数，并证明它们分别恰好对应 MSO 转换与一阶转换。
论文研究操作列表、列表的列表、列表对等嵌套结构的函数。作者定义了两类函数：正则列表函数与一阶列表函数，定义风格类似正则表达式：从投影、列表头尾等基本函数出发，通过四种组合子（最重要的是函数复合）构造。核心结果是：在合适的输入编码下，一阶列表函数恰好等同于一阶转换，而正则列表函数恰好等同于 MSO 转换。该工作为嵌套列表上的函数式程序提供了逻辑与自动机视角下的精确刻画，把正则表达式式的函数构造与逻辑转换统一起来。评估以数学证明和等价性定理为主，摘要未涉及实现或实验。
We define two classes of functions, called regular (respectively, first-order) list functions, which manipulate objects such as lists, lists of lists, pairs of lists, lists of pairs of lists, etc. The definition is in the style of regular expressions: the functions are constructed by starting with some basic functions (e.g. projections from pairs, or head and tail operations on lists) and putting them together using four combinators (most importantly, composition of functions). Our main results are that first-order list functions are exactly the same as first-order transductions, under a suitable encoding of the inputs; and the regular list functions are exactly the same as MSO-transductions.