String transductions that are definable in monadic second-order (mso) logic (without the use of parameters) are exactly those realized by deterministic two-way finite state transducers. Nondeterministic mso definable string transductions (i.e., those definable with the use of parameters) correspond to compositions of two nondeterministic two-way finite state transducers that have the finite visit property. Both families of mso definable string transductions are characterized in terms of Hennie machines, i.e., two-way finite state transducers with the finite visit property that are allowed to rewrite their input tape.
Characterizations of Monadic Second Order Definable Context-Free Sets of Graphs
Univ. Grenoble Alpes, CNRS, Grenoble INP, VERIMAG(格勒诺布尔阿尔卑斯大学、法国国家科学研究中心、格勒诺布尔理工学院、VERIMAG);Institute of Logic and Computation, Technische Universität Wien(维也纳工业大学逻辑与计算研究所)
可识别性定理指出,如果一组有限图可由一元二阶(Monadic Second Order,MSO)语句定义,则它相对于图代数是可识别的,而图宽度的定义是基于图代数的。可识别性是一个代数概念,用同余来定义,也可以用有限自动机来描述所考虑的图。该定理要求MSO图属性的验证,或者等价地,有限二元关系结构上的MSO逻辑的模型检验问题,对于由表示属性的公式和输入图或结构的树宽度(或树宽度)组成的参数是固定参数可处理的(FPT)。相应的算法可以通过飞行自动机来实现,其转换是在飞行中计算的,而不是列表。我们回顾了两个版本的可识别性,我们目前的苍蝇自动机的例子表明,他们也可以计算值附加到图。我们表明,飞自动机与无限的状态集产生一个简单的证明强版本的可识别性定理。这个证明以前没有发表过。