Skill Expansion and Composition in Parameter Space
Authors: name: Tenglong Liu, name: Jianxiong Li, name: Yinan Zheng, name: Haoyi Niu, name: Yixing Lan, name: Xin Xu, name: Xianyuan Zhan

Humans excel at reusing prior knowledge to address new challenges and
developing skills while solving problems. This paradigm becomes increasingly
popular in the development of autonomous agents, as it develops systems that
can self-evolve in response to new challenges like human beings. However,
previous methods suffer from limited training efficiency when expanding new
skills and fail to fully leverage prior knowledge to facilitate new task
learning. In this paper, we propose Parametric Skill Expansion and Composition
(PSEC), a new framework designed to iteratively evolve the agents' capabilities
and efficiently address new challenges by maintaining a manageable skill
library. This library can progressively integrate skill primitives as
plug-and-play Low-Rank Adaptation (LoRA) modules in parameter-efficient
finetuning, facilitating efficient and flexible skill expansion. This structure
also enables the direct skill compositions in parameter space by merging LoRA
modules that encode different skills, leveraging shared information across
skills to effectively program new skills. Based on this, we propose a
context-aware module to dynamically activate different skills to
collaboratively handle new tasks. Empowering diverse applications including
multi-objective composition, dynamics shift, and continual policy shift, the
results on D4RL, DSRL benchmarks, and the DeepMind Control Suite show that PSEC
exhibits superior capacity to leverage prior knowledge to efficiently tackle
new challenges, as well as expand its skill libraries to evolve the
capabilities. Project website: https://ltlhuuu.github.io/PSEC/.