Degenerations of representations and thin triangles

There is a compactification of the space of representations of a finitely generated group into the groups of isometries of all spaces with $\mathrm{\Delta }$-thin triangles. The ideal points are actions on $\mathbb{R}$-trees. It is a geometric reformulation and extension of the Culler-Morgan-Shalen theory concerning limits of representations into $\mathrm{SL}(2,\mathbb{C})$ and more generally $\mathrm{O}(n,1)$. This paper was written and circulated in the early 90’s, but never published.