Morphology and finite-state techniques

Question 1

Morpheme

Answer 1

Minimal information carrying units

Question 2

Affixes

Answer 2

Morphemes which can only occur in conjunction with other morphemes.

Question 3

Suffixes

Answer 3

Affixes which go after stem

Question 4

Prefixes

Answer 4

Affixes which go before stem - just derivational in english.

Question 5

Infixes

Answer 5

Affixes which occur inside the stem.

Question 6

Circumfixes

Answer 6

Affixes which go around the stem.

Question 7

Productive

Answer 7

The process of changing a word e.g. adding an affix, can be applied to new words such as adding s for plurals in english.

Question 8

Inflectional Morphology

Answer 8

Concerns properties such as tense, aspect, number, person, gender, and case.

Question 9

Derivational Morpholology

Answer 9

Using an affix to form a word on the basis of an existing word.

Question 10

Spelling Rules

Answer 10

Largely concatenative with some exceptions. There are however regular phonological and spelling changes associated with affixation e.g. e-insertion rule for plurals if word ends with s, x or z.

Question 11

Full-form lexicon

Answer 11

List all the inflected forms and treat derivational morphology as non-productive.

Question 12

Stemming

Answer 12

Strip endings to retrieve stem.

Question 13

Porter Stemmer

Answer 13

Uses a series of simple rules to strip endings.

Question 14

Lemmatisation

Answer 14

Analysing the form into a stem and affixes so that the necessary syntactic (and potentially semantic) information can be associated with it.

Question 15

Bidirectional

Answer 15

Can be used for analysis and generation.

Question 16

Lexical information needed for high precision morphological processing

Answer 16

Affixes - plus associated information conveyed by the affix.

Irregular forms - associated information similar to that for affixes.

Stems with syntactic categories.

Question 17

Why is a lexicon of regular stems necessary for high precision morphological analysis?

Answer 17

We need to avoid incorrectly analysing words e.g. analysing corpus as a plural of corpu. This also is important in cases where a word was historically derived but is now no longer found in the language.

Question 18

Local Ambiguity

Answer 18

Ambiguity that will be resolved by the subsequent context.

Question 19

Overgeneration

Answer 19

Generate all valid outputs but also some invalid outputs. This is often tolerable especially if only analysis is important.

Question 20

Finite State Transducers

Answer 20

Map between two representations so each transition corresponds to a pair of characters. FST only accepts input if ends in accept state.

Question 21

FSTs for Morphological Parsing

Answer 21

Morphology systems detect boundaries in analysis mode while in generation mode it can construct the correct string.

Question 22

Probabilistic FSAs

Answer 22

Can augment the FSA with informatino about transition probabilities.