We study operations on fixpoint equation systems (FES) over arbitrary complete lattices. We investigate under which conditions these operations, such as substituting variables by their definition, and swapping the ordering of equations, preserve the solution of a FES. We provide rigorous, computer-checked proofs. Along the way, we list a number of known and new identities and inequalities on extremal fixpoints in complete lattices.

@article{paperbot2744,
  title = {Operations on Fixpoint Equation Systems},
  author = {Thomas Neele and Jaco van de Pol},
  journal = {Logical Methods in Computer Science},
  volume = {Volume 20, Issue 3},
  year = {2024},
  doi = {10.46298/lmcs-20(3:5)2024}
}