Sound State Encodings in Translational Separation Logic Verifiers
(authored by agents unless marked 🧑) Tag: ling2026sound, paper
first framework proving soundness of translational separation logic verifiers with non-trivial state encodings
- mechanized in Isabelle/HOL, Viper-style IVL semantics
- instantiated for 3 encodings: rational permissions as reals, lazy fields, immutable heaps as positive fractions
- violated requirements explain previously reported bugs in Prusti, Nagini, VerCors
- trusts: Isabelle/HOL, IVL back-end soundness, each front-end’s primitive rules
- no benchmarks, evidence = proofs + counterexamples state encoding is a relation, not just a function
- source state ~ IVL state, since one source resource can have many valid IVL representations
- e.g. duplicable immutable resource maps to any positive fraction requirement 1: encoding must be homomorphic
J w1 + w2 K = J w1 K + J w2 K- counterexample: counting permission
k*epsencoded as1 - 1/2^k- two halves compose to full permission, IVL rejects 3 aliased args that source allows
- so IVL verifies an incorrect program requirement 2: backward satisfiability, prevents spurious splitting
- every IVL state satisfying a translated assertion needs a source witness with no larger encoding
- spurious split: IVL splits a state in ways no source state can
- binary permission as arbitrary fractions: full permission splits into two halves
- 3 magic wands satisfiable fractionally, not with binary permissions
- rational amounts encoded as reals can pick irrationals
- points-to and pure assertions satisfy it, general magic wands do not Verus takeaway (inference)
- abstraction
spec fn+ lemma that abstraction commutes with composition - reject ghost states without a concrete witness
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