Hi, i'm having some problems with the program. Currently, i'm using it to calculate one-loop diagrams in quantum gravity. The problems are that the kronecker delta does not completely disappear and that sometimes the algorithm "substitute" does not work. I have installed the software following the steps in the link "kpeeters/cadabra2" in the section "download" of the site. To be more precise, let $\Gamma_{\alpha\beta}$ be the 2-scalar-1 graviton vertex and $\Gamma_{\alpha\beta\mu\nu}$ be the 2 scalar- 2 graviton vertex. In the contraction $\Gamma_{\alpha\beta}\Gamma^{\alpha\beta\mu\nu}$, the substitution of $\Gamma_{\alpha\beta\mu\nu}$ occurs (sometimes) only after the distribute algorithm. I was thinking about the length of the components but I'm not sure. I have tried the combinations indices=free or fixed but it does not change. Kronecker delta still remains in every test. I hope in your response and I thank you in advance