Unni Cathrine Eiken February 2005

Figure 3
The most useful structure for the purpose of extracting EPAS from the parse output, is the MRS
structure. In comparison to the c- and f-structures, which are more syntactically motivated, the
MRS structure displays the semantic structure within a sentence. In the next section, this
structure is described in greater detail.
3.3.2.1 Minimal Recursion Semantics
Minimal Recursion Semantics (MRS), developed by Copestake et al. (2003), is a framework for
computational semantics, providing a meta-language for describing semantic structures. The
concept of MRS is primarily semantically motivated and aims at preserving the semantic
structures in the input sentence. MRS allows for expressive adequacy, ensuring that the
linguistic meanings conveyed by a sentence are expressed correctly in the semantic structure.
The primary unit within the framework of MRS is the elementary predication (EP). An EP is a
single relation with associated arguments and will generally speaking correspond to a lexeme
with its argument roles filled. Since MRS provides a “flat” representation where the EPs are
never nested within each other, semantically irrelevant implicit information about the syntactic
structure of a phrase is avoided. The simple principle is that each EP has a “handle” which
identifies it as belonging to a particular tree node and argument positions in EPs can be filled
with handles which correspond to the EPs that belong immediately under it in the tree structure.
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