This dataset represents the causal relationships amongst the four variables defined by Dambacher et al. in their 2005 publication in figure 2, page 10.
data(cm.DLR)
A 4 by 4 (-1, 0, 1) matrix with each element having at least one parent and at least one child. The matrix is interpreted as the jth variable has the direct causal effect a[i,j] on variable i.
Dambacher, J. M., R. Levins and P. A. Rossignol. (2005) Life expectancy change in perturbed communities: Derivation and qualitative analysis. Mathematical Biosciences 197,1--14. <tools:::Rd_expr_doi("10.1016/j.mbs.2005.06.001")>.