# Consistent Identification in the Limit of Any of the Classes k -Valued Is NP-hard

@inproceedings{Florncio2001ConsistentII, title={Consistent Identification in the Limit of Any of the Classes k -Valued Is NP-hard}, author={Christophe Costa Flor{\^e}ncio}, booktitle={LACL}, year={2001} }

In [Bus87], [BP90] 'discovery procedures' for CCGs were defined that accept a sequence of structures as input and yield a set of grammars.In [Kan98] it was shown that some of the classes based on these procedures are learnable (in the technical sense of [Gol67]). In [CF00] it was shown that learning some of these classes by means of a consistent learning function is NP-hard.The complexity of learning classes from one particular family, Gk-valued, was still left open. In this paper it is shown…

## 22 Citations

Consistent Identification in the Limit of Rigid Grammars from Strings Is NP-hard

- Computer ScienceICGI
- 2002

It is shown that the learning functions for these learnable classes are all NP-hard.

Fast Learning from Strings of 2-Letter Rigid Grammars

- Computer ScienceICGI
- 2002

The class of 2-letter rigid grammars is studied and it is shown thatgrammars in this class can be learned very efficiently, within Gold's paradigm of identification in the limit, from positive examples.

k-Valued Non-Associative Lambek Categorial Grammars are not Learnable from Strings

- Computer ScienceACL
- 2003

It is shown that the class of rigid and k-valued NL grammars is unlearnable from strings, for each k; this result is obtained by a specific construction of a limit point in the considered class, that does not use product operator.

A Learnable Class of CCGs from Typed Examples

- Computer Science
- 2003

A new way of considering learning Categorial Grammars from semantic knowledge is presented, and the hypothesis that semantic types, in the usual sense, are general information making a distinction between facts, is made.

A Learnable Class of Classical Categorial Grammars from Typed Examples

- Computer Science
- 2008

The main result is that for every CCG, a new subclass of CCGs with good properties from a language-theoretic point of view is defined.

On Limit Points for Some Variants of Rigid Lambek Grammars

- Computer ScienceICGI
- 2002

It is shown that in contrast to k-valued classical categorial grammars, different classes of Lambek Grammars are not learnable from strings following Gold's model.

Learning Recursive Automata from Positive Examples

- Computer ScienceRev. d'Intelligence Artif.
- 2006

This theoretical paper studies how to translate finite state automata into categorial grammars and back, and shows that the generalization operators employed in both domains can be compared and that their result can always be represented by generalized automata, called "recursive automata ".

When Categorial Grammars Meet Regular Grammatical Inference

- Computer ScienceLACL
- 2005

It is proved that every unidirectional categorial grammar, and thus every context-free language, can be represented by a new kind of finite-state generative model called a recursive automaton.

On Categorial Grammatical Inference and Logical Information Systems

- Computer ScienceStudies in Computational Intelligence
- 2019

This work considers several classes of categorial grammars and discusses their learnability, and considers the Logical Information Systems approach, that allows for navigation, querying, updating, and analysis of heterogeneous data collections where data are given (logical) descriptors.

Proceedings of FGVienna: The 8th conference on Formal Grammar

- Computer Science
- 2003

It is proved that the languages of link structured lists of words associated to rigid link grammars have finite elasticity and a learning algorithm is shown and this result leads to the learnability of rigid or k-valued link Grammars learned from strings.

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