Prove equivalences

[MaxOstrowski]

If someone is up for checking the difference traits for the level of equivalence, here are some pointers.

https://arxiv.org/pdf/1901.09127.pdf (Lierler, Y. (2022). Strong Equivalence and Program Structure in Arguing Essential Equivalence between Logic Programs. Theory and Practice of Logic Programming, 22(3), 335-366. doi:10.1017/S1471068421000545)

https://www.cambridge.org/core/journals/theory-and-practice-of-logic-programming/article/external-behavior-of-a-logic-program-and-verification-of-refactoring/ED81E6F82F1B560F8F19AB212D1F6E6B
Fandinno, J., Hansen, Z., Lierler, Y., Lifschitz, V., & Temple, N. (2023). External Behavior Of A Logic Program And Verification Of Refactoring. Theory And Practice Of Logic Programming, 23(4), 933-947. Doi:10.1017/s1471068423000200

[tortinator]

Thanks for putting this issue, @MaxOstrowski ! I guess it is important for @teiesti 's work.