JuliaReach is the Julia ecosystem for reachability computations of dynamical systems. Application domains of set-based reachability include formal verification, controller synthesis and estimation under uncertain model parameters or inputs. For further context reach us on the JuliaReach zulip stream. You may also refer to the review article Set Propagation Techniques for Reachability Analysis.
Difficulty: Medium.
Description. ReachabilityAnalysis is a Julia library for set propagation of dynamical systems. This project aims at integrating ReachabilityAnalysis with the numerical modeling ecosystem in Julia.
Expected Results. The proposal is to let the user specify models defined in ModelingToolkit.jl from the SciML ecosystem, and solve them using reachability methods. This first iteration would cover purely continuous systems; a second iteration would cover systems with discrete transitions (hybrid systems).
Expected Length. 175 hours.
Recommended Skills. Familiarity with Julia and Git/GitHub is mandatory. Familiarity with LazySets and ReachabilityAnalysis is welcome but not required.
Mentors: Marcelo Forets, Christian Schilling.
Difficulty: Medium.
Description. LazySets is the core library of JuliaReach. It provides ways to symbolically compute with geometric sets, with a focus on lazy set representations and efficient high-dimensional processing. The library has been described in the article LazySets.jl: Scalable Symbolic-Numeric Set Computations.
The main interest in this project is to implement algorithms that leverage the structure of the sets. Typical examples include polytopes and zonotopes (convex), polynomial zonotopes and Taylor models (non-convex) to name a few.
Expected Results. The goal is to implement certain efficient state-of-the-art algorithms from the literature. The code is to be documented, tested, and evaluated in benchmarks. Specific tasks may include (to be driven by the interets of the candidate): efficient vertex enumeration of zonotopes; operations on polynomial zonotopes; operations on zonotope bundles; efficient disjointness checks between different set types; complex zonotopes.
Expected Length. 175 hours.
Recommended Skills. Familiarity with Julia and Git/GitHub is mandatory. Familiarity with LazySets is recommended. Basic knowledge of geometric terminology is appreciated but not required.
Mentors: Marcelo Forets, Christian Schilling.
Difficulty: Medium.
Description. Sparse polynomial zonotopes are a new non-convex set representation that are well-suited for reachability analysis of nonlinear dynamical systems. This project is a continuation of GSoC'2022 - Reachability with sparse polynomial zonotopes, which implemented the basics in LazySets.
Expected Results. It is expected to add efficient Julia implementations of a reachability algorithm for dynamical systems in ReachabilityAnalysis which leverages polynomial zonotopes. A successful project should:
Replicate the results from the article Reachability Analysis for Linear Systems with Uncertain Parameters using Polynomial Zonotopes.
The code shall be documented, tested, and evaluated extensively in benchmarks.
For ambitious candidates it is possible to draw connections with neural-network control systems as implemented in ClosedLoopReachability.jl.
Expected Length. 175 hours.
Recommended Skills. Familiarity with Julia and Git/GitHub is mandatory. Familiarity with the mentioned Julia packages is appreciated but not required. The project does not require theoretical contributions, but it requires reading a research literature, hence a certain level of academic experience is recommended.
Literature and related packages. This video explains the concept of polynomial zonotopes (slides here). The relevant theory is described in this research article. There exists a Matlab implementation in CORA (the implementation of polynomial zonotopes can be found in this folder).
Mentors: Marcelo Forets, Christian Schilling.
Difficulty: Medium.
Description. ReachabilityAnalysis is a Julia library for set propagation of dynamical systems. One of the main aims is to handle systems with mixed discrete-continuous behaviors (known as hybrid systems in the literature). This project will focus on enhancing the capabilities of the library and overall improvement of the ecosystem for users.
Expected Results. Specific tasks may include: problem-specific heuristics for hybrid systems; API for time-varying input sets; flowpipe underapproximations. The code is to be documented, tested, and evaluated in benchmarks. Integration with ModelingToolkit.jl can also be considered if there is interest.
Expected Length. 175 hours.
Recommended Skills. Familiarity with Julia and Git/GitHub is mandatory. Familiarity with LazySets and ReachabilityAnalysis is welcome but not required.
Mentors: Marcelo Forets, Christian Schilling.