elim {dst}

Reduction of a relation

Description

This function works on a relation defined on a product of two variables or more. Having fixed a variable to eliminate from the relation, the reduced product space is determined and the corresponding reduced bca is computed.This operation is also called "marginalization".

Usage

elim(rel, xnb)

Arguments

rel

The relation to reduce, an object of class bcaspec.

xnb

Identification number of the variable to eliminate.

Value

r The reduced relation

Author(s)

Claude Boivin

Examples

 
# We construct a relation between two variables to show marginalization.
wr_tt <- matrix(c(1,rep(0,3),rep(c(1,0),3),0,1,1,1,0,0,
1,0,rep(1,5),0,1,1,0,rep(1,5)), ncol = 4, byrow = TRUE)
colnames(wr_tt) <- c("Wy Ry", "Wy Rn", "Wn Ry", "Wn Rn")
rownames(wr_tt) <- nameRows(wr_tt)
wr_spec = matrix(c(1:8, 0.017344, 0.046656, 
0.004336, 0.199456,0.011664,0.536544,0.049864, 0.134136), 
 ncol = 2, dimnames = list(NULL, c("specnb", "mass"))) 
 wr_infovar = matrix(c(4,5,2,2), ncol = 2, 
 dimnames = list(NULL, c("varnb", "size")) )
wr_rel <- list(tt = wr_tt, con = 0.16, spec=wr_spec,
  infovar = wr_infovar, varnames = c("Roadworks","Rain"),
  valuenames = list( RdWorks = c("Wy", "Wn"), Rain=c("Ry", "Rn") ))
class(wr_rel) <- "bcaspec"
bcaPrint(elim(wr_rel, xnb = 5))
bcaPrint(elim(wr_rel, xnb = 4))