node expansion
A Potential Negative Societal Impacts
We have not trained our models with sensitive or private data, and we emphasize that our model's direct L( n) other than the constant one as long as g (n) and l ( n) are positively correlated. The results for the baselines AdaSubS, kSubS, BC, CQL, DT, and HIPS with learned models were copied from [18]. The total number of GPU hours used on this work was approximately 7,500. We used 6 CPU workers (AMD Trento) per GPU. In the latter case, completeness cannot be guaranteed.
Subgoal-Guided Policy Heuristic Search with Learned Subgoals
Tuero, Jake, Buro, Michael, Lelis, Levi H. S.
Policy tree search is a family of tree search algorithms that use a policy to guide the search. These algorithms provide guarantees on the number of expansions required to solve a given problem that are based on the quality of the policy. While these algorithms have shown promising results, the process in which they are trained requires complete solution trajectories to train the policy. Search trajectories are obtained during a trial-and-error search process. When the training problem instances are hard, learning can be prohibitively costly, especially when starting from a randomly initialized policy. As a result, search samples are wasted in failed attempts to solve these hard instances. This paper introduces a novel method for learning subgoal-based policies for policy tree search algorithms. The subgoals and policies conditioned on subgoals are learned from the trees that the search expands while attempting to solve problems, including the search trees of failed attempts. We empirically show that our policy formulation and training method improve the sample efficiency of learning a policy and heuristic function in this online setting.
Bidirectional Bounded-Suboptimal Heuristic Search with Consistent Heuristics
Shperberg, Shahaf S., Morad, Natalie, Siag, Lior, Felner, Ariel, Atzmon, Dor
Recent advancements in bidirectional heuristic search have yielded significant theoretical insights and novel algorithms. While most previous work has concentrated on optimal search methods, this paper focuses on bounded-suboptimal bidirectional search, where a bound on the suboptimality of the solution cost is specified. We build upon the state-of-the-art optimal bidirectional search algorithm, BAE*, designed for consistent heuristics, and introduce several variants of BAE* specifically tailored for the bounded-suboptimal context. Through experimental evaluation, we compare the performance of these new variants against other bounded-suboptimal bidirectional algorithms as well as the standard weighted A* algorithm. Our results demonstrate that each algorithm excels under distinct conditions, highlighting the strengths and weaknesses of each approach.
A Potential Negative Societal Impacts
We have not trained our models with sensitive or private data, and we emphasize that our model's direct L( n) other than the constant one as long as g (n) and l ( n) are positively correlated. The results for the baselines AdaSubS, kSubS, BC, CQL, DT, and HIPS with learned models were copied from [18]. The total number of GPU hours used on this work was approximately 7,500. We used 6 CPU workers (AMD Trento) per GPU. In the latter case, completeness cannot be guaranteed.
V*: An Efficient Motion Planning Algorithm for Autonomous Vehicles
Andaryan, Abdullah Zareh, Bell, Michael G. H., Ramezani, Mohsen, Geers, Glenn
Autonomous vehicle navigation in structured environments requires planners capable of generating time-optimal, collision-free trajectories that satisfy dynamic and kinematic constraints. We introduce V*, a graph-based motion planner that represents speed and direction as explicit state variables within a discretised space-time-velocity lattice. Unlike traditional methods that decouple spatial search from dynamic feasibility or rely on post-hoc smoothing, V* integrates both motion dimensions directly into graph construction through dynamic graph generation during search expansion. T o manage the complexity of high-dimensional search, we employ a hexagonal discretisation strategy and provide formal mathematical proofs establishing optimal waypoint spacing and minimal node redundancy under constrained heading transitions for velocity-aware motion planning. We develop a mathematical formulation for transient steering dynamics in the kinematic bicycle model, modelling steering angle convergence with exponential behaviour, and deriving the relationship for convergence rate parameters. We further demonstrate V*'s performance in simulation studies with cluttered and dynamic environments involving moving obstacles, showing its ability to avoid conflicts, yield proactively, and generate safe, efficient trajectories with temporal reasoning capabilities for waiting behaviours and dynamic coordination. Autonomous navigation requires planning algorithms that can compute time-efficient and dynamically feasible trajectories. Among the diverse approaches to motion planning, optimal pathfinding algorithms are recognized for their ability to guarantee high-quality solutions by minimizing path costs under strict constraints. This makes them particularly valuable in environments where precision and efficiency are critical. Classical pathfinding methods such as the Dijkstra ( 1) and A* ( 2) algorithms have been widely adopted for solving shortest path problems on graphs due to their efficiency.
On Parallel External-Memory Bidirectional Search
Siag, Lior, Shperberg, Shahaf S., Felner, Ariel, Sturtevant, Nathan R.
Parallelization and External Memory (PEM) techniques have significantly enhanced the capabilities of search algorithms when solving large-scale problems. Previous research on PEM has primarily centered on unidirectional algorithms, with only one publication on bidirectional PEM that focuses on the meet-in-the-middle (MM) algorithm. Building upon this foundation, this paper presents a framework that integrates both uni- and bi-directional best-first search algorithms into this framework. We then develop a PEM variant of the state-of-the-art bidirectional heuristic search (BiHS) algorithm BAE* (PEM-BAE*). As previous work on BiHS did not focus on scaling problem sizes, this work enables us to evaluate bidirectional algorithms on hard problems. Empirical evaluation shows that PEM-BAE* outperforms the PEM variants of A* and the MM algorithm, as well as a parallel variant of IDA*. These findings mark a significant milestone, revealing that bidirectional search algorithms clearly outperform unidirectional search algorithms across several domains, even when equipped with state-of-the-art heuristics.