Planning & Scheduling
Goal Reasoning: Foundations, Emerging Applications, and Prospects
Goal reasoning (GR) has a bright future as a foundation for the research and development of intelligent agents. GR is the study of agents that can deliberate on and self-select their goals/objectives, which is a desirable capability for some applications of deliberative autonomy. While studied in diverse AI sub-communities for multiple applications, our group has focused on how GR can play a key role for controlling autonomous systems. Thus, its importance is rapidly growing and it merits increased attention, particularly from the perspective of research on AI safety. In this article, I introduce GR, briefly relate it to other AI topics, summarize some of our group’s work on GR foundations and emerging applications, and describe some current and future research directions.
Extending Classical Planning with State Constraints: Heuristics and Search for Optimal Planning
Haslum, Patrik, Ivankovic, Franc, Ramirez, Miquel, Gordon, Dan, Thiebaux, Sylvie, Shivashankar, Vikas, Nau, Dana S.
We present a principled way of extending a classical AI planning formalism with systems of state constraints, which relate - sometimes determine - the values of variables in each state traversed by the plan. This extension occupies an attractive middle ground between expressivity and complexity. It enables modelling a new range of problems, as well as formulating more efficient models of classical planning problems. An example of the former is planning-based control of networked physical systems - power networks, for example - in which a local, discrete control action can have global effects on continuous quantities, such as altering flows across the entire network. At the same time, our extension remains decidable as long as the satisfiability of sets of state constraints is decidable, including in the presence of numeric state variables, and we demonstrate that effective techniques for cost-optimal planning known in the classical setting - in particular, relaxation-based admissible heuristics - can be adapted to the extended formalism. In this paper, we apply our approach to constraints in the form of linear or non-linear equations over numeric state variables, but the approach is independent of the type of state constraints, as long as there exists a procedure that decides their consistency. The planner and the constraint solver interact through a well-defined, narrow interface, in which the solver requires no specialisation to the planning context.
Dynamic Assortment Selection under the Nested Logit Models
Chen, Xi, Wang, Yining, Zhou, Yuan
We study a stylized dynamic assortment planning problem during a selling season of finite length $T$, by considering a nested multinomial logit model with $M$ nests and $N$ items per nest. Our policy simultaneously learns customers' choice behavior and makes dynamic decisions on assortments based on the current knowledge. It achieves the regret at the order of $\tilde{O}(\sqrt{MNT}+MN^2)$, where $M$ is the number of nests and $N$ is the number of products in each nest. We further provide a lower bound result of $\Omega(\sqrt{MT})$, which shows the optimality of the upper bound when $T>M$ and $N$ is small. However, the $N^2$ term in the upper bound is not ideal for applications where $N$ is large as compared to $T$. To address this issue, we further generalize our first policy by introducing a discretization technique, which leads to a regret of $\tilde{O}(\sqrt{M}T^{2/3}+MNT^{1/3})$ with a specific choice of discretization granularity. It improves the previous regret bound whenever $N>T^{1/3}$. We provide numerical results to demonstrate the empirical performance of both proposed policies.
The Art of Drafting: A Team-Oriented Hero Recommendation System for Multiplayer Online Battle Arena Games
Chen, Zhengxing, Nguyen, Truong-Huy D, Xu, Yuyu, Amato, Chris, Cooper, Seth, Sun, Yizhou, El-Nasr, Magy Seif
Multiplayer Online Battle Arena (MOBA) games have received increasing popularity recently. In a match of such games, players compete in two teams of five, each controlling an in-game avatars, known as heroes, selected from a roster of more than 100. The selection of heroes, also known as pick or draft, takes place before the match starts and alternates between the two teams until each player has selected one hero. Heroes are designed with different strengths and weaknesses to promote team cooperation in a game. Intuitively, heroes in a strong team should complement each other's strengths and suppressing those of opponents. Hero drafting is therefore a challenging problem due to the complex hero-to-hero relationships to consider. In this paper, we propose a novel hero recommendation system that suggests heroes to add to an existing team while maximizing the team's prospect for victory. To that end, we model the drafting between two teams as a combinatorial game and use Monte Carlo Tree Search (MCTS) for estimating the values of hero combinations. Our empirical evaluation shows that hero teams drafted by our recommendation algorithm have significantly higher win rate against teams constructed by other baseline and state-of-the-art strategies.
CASP Solutions for Planning in Hybrid Domains
Balduccini, Marcello, Magazzeni, Daniele, Maratea, Marco, LeBlanc, Emily
CASP is an extension of ASP that allows for numerical constraints to be added in the rules. PDDL+ is an extension of the PDDL standard language of automated planning for modeling mixed discrete-continuous dynamics. In this paper, we present CASP solutions for dealing with PDDL+ problems, i.e., encoding from PDDL+ to CASP, and extensions to the algorithm of the EZCSP CASP solver in order to solve CASP programs arising from PDDL+ domains. An experimental analysis, performed on well-known linear and non-linear variants of PDDL+ domains, involving various configurations of the EZCSP solver, other CASP solvers, and PDDL+ planners, shows the viability of our solution.
A New Approach for Resource Scheduling with Deep Reinforcement Learning
Ye, Yufei, Ren, Xiaoqin, Wang, Jin, Xu, Lingxiao, Guo, Wenxia, Huang, Wenqiang, Tian, Wenhong
With the rapid development of deep learning, deep reinforcement learning (DRL) began to appear in the field of resource scheduling in recent years. Based on the previous research on DRL in the literature, we introduce online resource scheduling algorithm DeepRM2 and the offline resource scheduling algorithm DeepRM_Off. Compared with the state-of-the-art DRL algorithm DeepRM and heuristic algorithms, our proposed algorithms have faster convergence speed and better scheduling efficiency with regarding to average slowdown time, job completion time and rewards.
American expects back to normal operations at regional unit
FORT WORTH, Texas – American Airlines says a regional affiliate should run close to a normal operation Thursday after canceling 2,750 flights in the past week because of a computer problem. Spokeswoman Katie Cody said PSA Airlines stabilized its computer systems but faced delays getting planes and crews back in place. Based in Dayton, Ohio, PSA is owned by American and operates many American Eagle regional flights, especially in Charlotte, North Carolina. Cody said American has been rebooking stranded passengers on American and other airlines since disruptions started June 14. She said there was a hardware problem in computers used to run crew-scheduling applications.
American Airlines Suffers The Latest Airline IT Meltdown
Within the span of a month during the summer of 2016, two of the top four U.S. airlines suffered crippling IT failures. Delta Air Lines (NYSE:DAL) and Southwest Airlines (NYSE:LUV) were each forced to cancel thousands of flights during the peak season, leading to lost revenue and reputational damage. This article originally appeared in the Motley Fool. The summer 2018 peak season is just getting started, but there has already been a major airline IT failure. In the past week, flight cancellations have rapidly mounted at American Airlines' (NASDAQ:AAL) regional subsidiary PSA Airlines, due to problems with the carrier's crew scheduling system.
Validation of Hierarchical Plans via Parsing of Attribute Grammars
Bartak, Roman (Charles University) | Maillard, Adrien (Charles University) | Cardoso, Rafael Cauê ( Pontifícia Universidade Católica do Rio Grande do Sul )
An important problem of automated planning is validating if a plan complies with the domain model. Such validation is straightforward for classical sequential planning but until recently there was no plan validation approach for Hierarchical Task Networks (HTN). In this paper we propose a novel technique for validating HTN plans by parsing of attribute grammars with the timeline constraint.
RMPD — A Recursive Mid-Point Displacement Algorithm for Path Planning
Li, Fangda (Purdue University) | Manerikar, Ankit V. (Purdue University) | Kak, Avinash C. (Purdue University)
Motivated by what is required for real-time path planning, the paper starts out by presenting RMPD, a new recursive ''local'' planner founded on the key notion that, unless made necessary by an obstacle, there must be no deviation from the shortest path between any two points, which would normally be a straight line path in the configuration space. Subsequently, we increase the power of RMPD by introducing the notion of cost-awareness into the algorithm to improve the path quality -- this is done by associating obstacle and smoothness costs with the currently selected path points and factoring those costs in choosing the best points for the next iteration. In this manner, the overall strategy in the cost-aware form of RMPD, cRMPD, combines the computational efficiency made possible by the recursive RMPD planner with the cost efficacy of a stochastic trajectory optimizer to rapidly produce high-quality local collision-free paths. Based on the test cases we have run, our experiments show that cRMPD can reduce planning time by up to two orders of magnitude as compared to RRT-Connect, while still maintaining a path length optimality equivalent to that of RRT*.