We study the modified Martínez Alonso–Shabat equation$u_y{u}_{xz}+\alpha u_x{u}_{ty}-(u_z+\alpha u_t)u_{xy}=0$and present its recursion operator and an infinite commuting hierarchy of full-fledged nonlocal symmetries. To date such hierarchies were found only for very few integrable systems in more than three independent variables.

中文翻译：

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修正的MartínezAlonso–Shabat方程的无穷多个通勤非局部对称性

我们研究了修正的MartínezAlonso–Shabat方程${ü}_{ÿ}{ü}_{Xž}+\alpha {ü}_X{ü}_{Ťÿ}-（{ü}_{ž}+\alpha {ü}_{Ť}）{ü}_{Xÿ}=0$并给出其递归运算符和成熟的非局部对称性的无限换向层次。迄今为止，只有在三个以上自变量中的极少数可集成系统中才发现这种层次结构。