Monitor Circuits for LTL with Bounded and Unbounded Future

Abstract

Abstract. Synthesizing monitor circuits for LTL formulas is expensive, because the number of flip-flops in the circuit is exponential in the length of the formula. As a result, the IEEE standard PSL recommends to restrict monitoring to the simple subset and use the full logic only for static verification. We present a novel construction for the synthesis of monitor circuits from specifications in LTL. In our construction, only subformulas with unbounded-future operators contribute to the exponential blowup. We split the specification into a bounded and an unbounded part, apply specialized constructions for each part, and then compose the results into a monitor for the original specification. Since the unbounded part in practical specifications is often very small, we argue that, with the new construction, it is no longer necessary to restrict runtime verification to the simple subset.

Online Monitoring of Metric Temporal Logic

“…The most closely related work to the present paper is that of Finkbeiner and Kuhtz [11], which concerns monitoring MTL over a discrete-time semantics. They handle bounded formulas in a similar fashion to us and highlight the problematic role of unbounded temporal operators.…”

On-Line Monitoring for Temporal Logic Robustness

“…Our monitor uses bounded memory and, in the worst case, it has quadratic time complexity that depends on the magnitude of Hrz − Hst. In principle, our solution for robustness monitoring is inspired by the boolean temporal logic monitoring algorithm in [2].…”

“…The supervisor can then decide on remedial actions to fix the problem or reduce its impact to the system. The monitoring problem has been extensively studied [2][3][4][5][6][7][8][9][10][11][12][13][14] for the cases where the formal requirements are expressed in Linear Temporal Logic (LTL) [15] or in Metric Temporal Logic (MTL) [16].…”

Efficient Model Checking of PSL Safety Properties

“…Our encoding handles a strictly larger syntactic subset of PSL safety properties but is not directly suitable for runtime monitoring, as we use nondeterminism in the generated transducers for better succinctness. Our approach is designed to be used in combination with model checking algorithms and is thus significantly more succinct than the approach of [11] tailored to be used in runtime monitoring of PSL in a simulation setting. The approach of [4] for encoding informative bad prefixes for LTL formulas has been implemented in the scheck tool [12] in the context of explicit state model checking.…”