  Adapter-style efficient transfer learning (ETL) has shown excellent
performance in the tuning of vision-language models (VLMs) under the low-data
regime, where only a few additional parameters are introduced to excavate the
task-specific knowledge based on the general and powerful representation of
VLMs. However, most adapter-style works face two limitations: (i) modeling
task-specific knowledge with a single modality only; and (ii) overlooking the
exploitation of the inter-class relationships in downstream tasks, thereby
leading to sub-optimal solutions. To mitigate that, we propose an effective
adapter-style tuning strategy, dubbed GraphAdapter, which performs the textual
adapter by explicitly modeling the dual-modality structure knowledge (i.e., the
correlation of different semantics/classes in textual and visual modalities)
with a dual knowledge graph. In particular, the dual knowledge graph is
established with two sub-graphs, i.e., a textual knowledge sub-graph, and a
visual knowledge sub-graph, where the nodes and edges represent the
semantics/classes and their correlations in two modalities, respectively. This
enables the textual feature of each prompt to leverage the task-specific
structure knowledge from both textual and visual modalities, yielding a more
effective classifier for downstream tasks. Extensive experimental results on 11
benchmark datasets reveal that our GraphAdapter significantly outperforms
previous adapter-based methods. The code will be released at
https://github.com/lixinustc/GraphAdapter
