Nested Multisets, Hereditary Multisets, and Syntactic Ordinals in Isabelle/HOL

@inproceedings{Blanchette2017NestedMH,
  title={Nested Multisets, Hereditary Multisets, and Syntactic Ordinals in Isabelle/HOL},
  author={Jasmin Christian Blanchette and Mathias Fleury and Dmitriy Traytel},
  booktitle={FSCD},
  year={2017}
}
We present a collection of formalized results about finite nested multisets, developed using the Isabelle/HOL proof assistant. The nested multiset order is a generalization of the multiset order that can be used to prove termination of processes. Hereditary multisets, a variant of nested multisets, offer a convenient representation of ordinals below 0. In Isabelle/HOL, both nested and hereditary multisets can be comfortably defined as inductive datatypes. Our formal library also provides… 

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