# credal: Constructor Function for Credal Sets (based on intervals) In EvCombR: Evidence Combination in R

## Description

Construct a credal set based on probability intervals or a single probability function. The algorithm used for finding the extreme points corresponding to lower and upper bounds is described in De Campos et al. (1994).

## Usage

 `1` ```credal(x, y, z) ```

## Arguments

 `x` lower bounds of probability intervals (in the form of a numeric vector) `y` upper bounds for probability intervals or missing (i.e., upper bound of `1`) `z` character vector representing the state space

## Value

A credal set represented by a set of extreme points.

## Author(s)

Alexander Karlsson

## References

Levi, I. (1983), The enterprise of knowledge, The MIT press

Arnborg, S. (2006), Robust Bayesianism: Relation to Evidence Theory, Journal of Advances in Information Fusion, 1, 63-74

Karlsson, A., Johansson, R., Andler, S. F. (2011), Characterization and Empirical Evaluation of Bayesian and Credal Combination Operators, Journal of Advances in Information Fusion, 6, 150-166

De Campos L. M., Huete, J. F., Moral S., Probability Intervals: a Tool for Uncertain Reasoning,International Journal of Uncertainty, Fuzziness, and Knowledge-Based Systems, 2, 167-196

`cComb`
 ```1 2 3 4 5 6 7 8``` ```# state space stateSpace <- c("a", "b", "c") # lower and upper bounds for probability intervals c1 <- credal(c(0.1, 0.1, 0.1), c(0.8, 0.8, 0.8), stateSpace) # single probability function (lower and upper bounds of probability intervals are equal) c2 <- credal(c(0.1, 0.2, 0.7), c(0.1, 0.2, 0.7), stateSpace) ```