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1

More information can be found in [BL93].

2

See [FPT97] for a survey of applying machine learning techniques to this database. A good introduction to machine learning can be found in [Mit96].

3

Also sometimes referred to as (recursive) sums of products. See, for example, [Win93] for a formal treatment.

4

See [WH00] for such a survey.

5

It may be interesting to point out that algebraic datatypes (sums of products) actually form a semi-ring. This also means that they are isomorphic to, for example, context-free grammars. This again implies that this representation is suitable for learning problems in the domain of natural language processing: it can essentially be used to induce (tree) transducers for parse trees originating from context-free languages.

6

Types (sets) are written italic whereas constructors are written in bold letters.

7

Like value orderings, this pattern is quite frequent in the database (e.g. see also variable CM29, D7, etc.

8

Note that irrelevant values are usually an indicator for redundant information so you might consider reorganizing your data specification.