Abstract
We investigate the notion of ‘infinitary strong normalization’ (SN ∞ ), introduced in [6], the analogue of termination when rewriting infinite terms. A (possibly infinite) term is SN ∞ if along every rewrite sequence each fixed position is rewritten only finitely often. In [9], SN ∞ has been investigated as a system-wide property, i.e. SN ∞ for all terms of a given rewrite system. This global property frequently fails for trivial reasons. For example, in the presence of the collapsing rule tail(x:σ)→σ, the infinite term t =tail(0:t) rewrites to itself only. Moreover, in practice one usually is interested in SN ∞ of a certain set of initial terms. We give a complete characterization of this (more general) ‘local version’ of SN ∞ using interpretations into weakly monotone algebras (as employed in [9]). Actually, we strengthen this notion to continuous weakly monotone algebras (somewhat akin to [5]). We show that tree automata can be used as an automatable instance of our framework; an actual implementation is made available along with this paper.
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Endrullis, J., Grabmayer, C., Hendriks, D., Klop, J.W., de Vrijer, R. (2009). Proving Infinitary Normalization. In: Berardi, S., Damiani, F., de’Liguoro, U. (eds) Types for Proofs and Programs. TYPES 2008. Lecture Notes in Computer Science, vol 5497. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-02444-3_5
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DOI: https://doi.org/10.1007/978-3-642-02444-3_5
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