Master's Thesis: Probabilistic Formal Verification

Introduction:

Thesis project at Scania is an excellent way of making contacts for your future working life. Many of our current employees started their career with a thesis project.

Background:

Modern vehicles rely increasingly on computers to operate properly and Scania is among the companies aiming to sell fully autonomous vehicles within the next few years.

Therefore, the correctness of software at Scania, and in the automotive industry in general, is essential. Exhaustively verifying system correctness can be done using formal verification, which means using mathematical reasoning to prove that a system fulfils some formal specification. However, current methods for formal verification require extensive time, resources and knowledge, and have therefore not yet been widely adopted in the automotive industry.

When driving in the real world, probabilities often arise due to random hardware failures, stochastic communication delays, sensor ghost objects, machine learning components, rounding errors, human behavior, and probabilistic algorithms.

Therefore, vehicle specifications must take probabilities into account. Using probabilistic contracts to specify allowed vehicle behaviors, checking that a vehicle fulfils its contract can be done according to the following three steps:

1. Decompose the vehicle contract into component contracts.

1. Verify the correctness of the decomposition.

1. Verify that each component fulfils its contract.

In most cases, current techniques for formal verification lack the generality and efficiency to successfully complete the above three steps.