  The paper presents an approach to semantic grounding of language models (LMs)
that conceptualizes the LM as a conditional model generating text given a
desired semantic message formalized as a set of entity-relationship triples. It
embeds the LM in an auto-encoder by feeding its output to a semantic parser
whose output is in the same representation domain as the input message.
Compared to a baseline that generates text using greedy search, we demonstrate
two techniques that improve the fluency and semantic accuracy of the generated
text: The first technique samples multiple candidate text sequences from which
the semantic parser chooses. The second trains the language model while keeping
the semantic parser frozen to improve the semantic accuracy of the
auto-encoder. We carry out experiments on the English WebNLG 3.0 data set,
using BLEU to measure the fluency of generated text and standard parsing
metrics to measure semantic accuracy. We show that our proposed approaches
significantly improve on the greedy search baseline. Human evaluation
corroborates the results of the automatic evaluation experiments.
