Counterfactual explanations are usually generated through heuristics that are
sensitive to the search's initial conditions. The absence of guarantees of
performance and robustness hinders trustworthiness. In this paper, we take a
disciplined approach towards counterfactual explanations for tree ensembles. We
advocate for a model-based search aiming at "optimal" explanations and propose
efficient mixed-integer programming approaches. We show that isolation forests
can be modeled within our framework to focus the search on plausible
explanations with a low outlier score. We provide comprehensive coverage of
additional constraints that model important objectives, heterogeneous data
types, structural constraints on the feature space, along with resource and
actionability restrictions. Our experimental analyses demonstrate that the
proposed search approach requires a computational effort that is orders of
magnitude smaller than previous mathematical programming algorithms. It scales
up to large data sets and tree ensembles, where it provides, within seconds,
systematic explanations grounded on well-defined models solved to optimality.

本文提出了一种基于模型的搜索方法，利用混合整数规划技术生成了对树集的对抗性解释，并通过隔离森林模型针对低异常得分的合理解释进行优化。

树集成中的最优反事实解释

Optimal Counterfactual Explanations in Tree Ensembles

Data efficiency and robustness to task-irrelevant perturbations are
long-standing challenges for deep reinforcement learning algorithms. Here we
introduce a modular approach to addressing these challenges in a continuous
control environment, without using hand-crafted or supervised information. Our
Curious Object-Based seaRch Agent (COBRA) uses task-free intrinsically
motivated exploration and unsupervised learning to build object-based models of
its environment and action space. Subsequently, it can learn a variety of tasks
through model-based search in very few steps and excel on structured hold-out
tests of policy robustness.

该研究提出了一种基于 Curious Object-Based seaRch Agent（ COBRA）的深度强化学习算法来提高数据效率和鲁棒性，其使用自主探索和无监督学习建立环境和动作空间的基于对象的模型，在极少的步骤中通过基于模型的搜索学习各种任务并在政策稳健性结构化保持测试中表现出色。