  Head-driven phrase structure grammar (HPSG) enjoys a uniform formalism
representing rich contextual syntactic and even semantic meanings. This paper
makes the first attempt to formulate a simplified HPSG by integrating
constituent and dependency formal representations into head-driven phrase
structure. Then two parsing algorithms are respectively proposed for two
converted tree representations, division span and joint span. As HPSG encodes
both constituent and dependency structure information, the proposed HPSG
parsers may be regarded as a sort of joint decoder for both types of structures
and thus are evaluated in terms of extracted or converted constituent and
dependency parsing trees. Our parser achieves new state-of-the-art performance
for both parsing tasks on Penn Treebank (PTB) and Chinese Penn Treebank,
verifying the effectiveness of joint learning constituent and dependency
structures. In details, we report 96.33 F1 of constituent parsing and 97.20\%
UAS of dependency parsing on PTB.
