BC.LU.approximation.RST: Computation of lower and upper approximations of decision...
In RoughSets: Data Analysis Using Rough Set and Fuzzy Rough Set Theories

Description Usage Arguments Details Value Author(s) References See Also Examples

This function implements a fundamental part of RST: computation of lower and upper approximations. The lower and upper approximations determine whether the objects can be certainty or possibly classified to a particular decision class on the basis of available knowledge.

1	BC.LU.approximation.RST(decision.table, IND)

`decision.table`	an object inheriting from the `"DecisionTable"` class, which represents a decision system. See `SF.asDecisionTable`.
`IND`	an object inheriting from the `"IndiscernibilityRelation"` class, which represents indiscernibility clasees in the data.

This function can be used as a basic building block for development of other RST-based methods. A more detailed explanation of this notion can be found in A.Introduction-RoughSets.

An object of a class "LowerUpperApproximation" which is a list with the following components:

lower.approximation: a list with indices of data instances included in lower approximations of decision classes.
upper.approximation: a list with indices of data instances included in upper approximations of decision classes.
type.model: a character vector identifying the type of model which was used. In this case, it is "RST" which means the rough set theory.

Andrzej Janusz

Z. Pawlak, "Rough Sets", International Journal of Computer and Information Sciences, vol. 11, no. 5, p. 341 - 356 (1982).

BC.IND.relation.RST, BC.LU.approximation.FRST

#######################################
data(RoughSetData)
hiring.data <- RoughSetData$hiring.dt

## We select a single attribute for computation of indiscernibility classes:
A <- c(2)

## Compute the indiscernibility classes:
IND.A <- BC.IND.relation.RST(hiring.data, feature.set = A)

## Compute the lower and upper approximations:
roughset <- BC.LU.approximation.RST(hiring.data, IND.A)
roughset