  Generative approaches powered by large language models (LLMs) have
demonstrated emergent abilities in tasks that require complex reasoning
abilities. Yet the generative nature still makes the generated content suffer
from hallucinations, thus unsuitable for entity-centric tasks like entity
linking (EL) requiring precise entity predictions over a large knowledge base.
We present Instructed Generative Entity Linker (INSGENEL), the first approach
that enables casual language models to perform entity linking over knowledge
bases. Several methods to equip language models with EL capability were
proposed in this work, including (i) a sequence-to-sequence training EL
objective with instruction-tuning, (ii) a novel generative EL framework based
on a light-weight potential mention retriever that frees the model from heavy
and non-parallelizable decoding, achieving 4$\times$ speedup without compromise
on linking metrics. INSGENEL outperforms previous generative alternatives with
+6.8 F1 points gain on average, also with a huge advantage in training data
efficiency and training compute consumption. In addition, our skillfully
engineered in-context learning (ICL) framework for EL still lags behind
INSGENEL significantly, reaffirming that the EL task remains a persistent
hurdle for general LLMs.
