In classical planning, the goal is to derive a course of actions that allows
an intelligent agent to move from any situation it finds itself in to one that
satisfies its goals. Classical planning is considered domain-independent, i.e.,
it is not limited to a particular application and can be used to solve
different types of reasoning problems. In practice, however, some properties of
a planning problem at hand require an expressive extension of the standard
classical planning formalism to capture and model them. Although the importance
of many of these extensions is well known, most planners, especially optimal
planners, do not support these extended planning formalisms. The lack of
support not only limits the use of these planners for certain problems, but
even if it is possible to model the problems without these extensions, it often
leads to increased effort in modeling or makes modeling practically impossible
as the required problem encoding size increases exponentially.
In this thesis, we propose to use symbolic search for cost-optimal planning
for different expressive extensions of classical planning, all capturing
different aspects of the problem. In particular, we study planning with axioms,
planning with state-dependent action costs, oversubscription planning, and
top-k planning. For all formalisms, we present complexity and compilability
results, highlighting that it is desirable and even necessary to natively
support the corresponding features. We analyze symbolic heuristic search and
show that the search performance does not always benefit from the use of a
heuristic and that the search performance can exponentially deteriorate even
under the best possible circumstances, namely the perfect heuristic. This
reinforces that symbolic blind search is the dominant symbolic search strategy
nowadays, on par with other state-of-the-art cost-optimal planning
strategies...

在经典计划中，为了满足智能体的目标，目标是制定一系列行动方案。扩展规划是用于捕获和模拟不同类型的推理问题的一种表达方式。本文中，我们提出使用符号搜索进行成本最优规划，为经典计划的不同表达扩展，包括公理、状态依赖性操作成本、过度订阅计划和前 k 个计划。

符号搜索与表达式扩展的最优规划

Symbolic Search for Optimal Planning with Expressive Extensions

We investigate the problem of cost-optimal planning in ASP. Current ASP
planners can be trivially extended to a cost-optimal one by adding weak
constraints, but only for a given makespan (number of steps). It is desirable
to have a planner that guarantees global optimality. In this paper, we present
two approaches to addressing this problem. First, we show how to engineer a
cost-optimal planner composed of two ASP programs running in parallel. Using
lessons learned from this, we then develop an entirely new approach to
cost-optimal planning, stepless planning, which is completely free of makespan.
Experiments to compare the two approaches with the only known cost-optimal
planner in SAT reveal good potentials for stepless planning in ASP. The paper
is under consideration for acceptance in TPLP.

该篇论文研究了 ASP 中成本最优规划问题，提出了基于两个 ASP 程序运行的成本最优规划器和完全不受制于步数的规划方法 Stepless Planning 来解决该问题，并实验结果表明 Stepless Planning 具有广阔的潜力。