Introduction

The XTAG system can handle sentences with conjunction of two constituents of the same syntactic category. The coordinating conjunctions which select the conjunction trees are and, or and but.^22.1 There are also multi-word conjunction trees, anchored by either-or, neither-nor, both-and, and as well as. There are eight syntactic categories that can be coordinated, and in each case an auxiliary tree is used to implement the conjunction. These eight categories can be considered as four different cases, as described in the following sections. In all cases the two constituents are required to be of the same syntactic category, but there may also be some additional constraints, as described below.