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Ordering Constraints over Feature Trees
, 1999
"... Feature trees are the formal basis for algorithms manipulating record like structures in constraint programming, computational linguistics and in concrete applications like software configuration management. Feature trees model records, and constraints over feature trees yield extensible and modular ..."
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Cited by 14 (5 self)
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Feature trees are the formal basis for algorithms manipulating record like structures in constraint programming, computational linguistics and in concrete applications like software configuration management. Feature trees model records, and constraints over feature trees yield extensible and modular record descriptions. We introduce the constraint system FT of ordering constraints interpreted over feature trees. Under the view that feature trees represent symbolic information, the relation corresponds to the information ordering ("carries less information than"). We present two algorithms in cubic time, one for the satisfiability problem and one for the entailment problem of FT . We show that FT has the independence property. We are thus able to handle negative conjuncts via entailment and obtain a cubic algorithm that decides the satisfiability of conjunctions of positive and negated ordering constraints over feature trees. Furthermore, we reduce the satisfiability problem of Dorre's weak subsumption constraints to the satisfiability problem of FT and improve the complexity bound for solving weak subsumption constraints from O(n^5) to O(n³).
Fibred Semantics for FeatureBased Grammar Logic
, 1994
"... This paper gives a simple method for providing categorial brands of featurebased unification grammars with a modeltheoretic semantics. The key idea is to apply the paradigm of fibred semantics (or layered logics, see [15]) in order to combine the two components of a featurebased grammar logic. We ..."
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Cited by 12 (5 self)
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This paper gives a simple method for providing categorial brands of featurebased unification grammars with a modeltheoretic semantics. The key idea is to apply the paradigm of fibred semantics (or layered logics, see [15]) in order to combine the two components of a featurebased grammar logic. We demonstrate the method for the augmentation of Lambek categorial grammar with Kasper/Roundsstyle feature logic. These are combined by replacing (or annotating) atomic formulas of the first logic, i.e. the basic syntactic types, by formulas of the second. Modelling such a combined logic is less trivial than one might expect. The direct application of the fibred semantics method where a combined atomic formula like np(num:sg & pers:3rd) denotes those strings which have the indicated property and the categorial operators denote the usual left and rightresiduals of these string sets, does not match the intuitive, unificationbased proof theory. Unification implements a global bookkeeping w...