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Creators/Authors contains: "Tripakis, Stavros"

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  1. Shielding is an effective method for ensuring safety in multi-agent domains; however, its applicability has previously been limited to environments for which an approximate discrete model and safety specification are known in advance. We present a method for learning shields in cooperative fully-observable multi-agent environments where neither a model nor safety specification are provided, using architectural constraints to realize several important properties of a shield. We show through a series of experiments that our learned shielding method is effective at significantly reducing safety violations, while largely maintaining the ability of an underlying reinforcement learning agent to optimize for reward. 
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    Free, publicly-accessible full text available May 19, 2026
  2. Abstract We present a novel counterexample-guided, sketch-based method for the synthesis of symbolic distributed protocols in TLA+. Our method’s chief novelty lies in a new search space reduction technique called interpretation reduction, which allows to not only eliminate incorrect candidate protocols before they are sent to the verifier, but also to avoid enumerating redundant candidates in the first place. Further performance improvements are achieved by an advanced technique for exact generalization of counterexamples. Experiments on a set of established benchmarks show that our tool is almost always faster than the state of the art, often by orders of magnitude, and was also able to synthesize an entire TLA+protocol “from scratch” in less than 3 minutes where the state of the art timed out after an hour. Our method is sound, complete, and guaranteed to terminate on unrealizable synthesis instances under common assumptions which hold in all our benchmarks. 
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    Free, publicly-accessible full text available May 1, 2026
  3. Shielding is an effective method for ensuring safety in multi-agent domains; however, its applicability has previously been limited to environments for which an approximate discrete model and safety specification are known in advance. We present a method for learning shields in cooperative fully-observable multi-agent environments where neither a model nor safety specification are provided, using architectural constraints to realize several important properties of a shield. We show through a series of experiments that our learned shielding method is effective at significantly reducing safety violations, while largely maintaining the ability of an underlying reinforcement learning agent to optimize for reward. 
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    Free, publicly-accessible full text available April 23, 2026