# Sigma and Pi Chemistry/Math Permutation Question

Does anyone know if sigma and pi bonds in chemistry have any mathematical definition? The reason I'm asking this is because I've recently read a lot about cycles and permutations, and they seem to primarily use sigma and pi in their notation when multiplying 2 separate cycles. Just a heads up, it might not even be related and was just curious.

• They're not related. It's just that $\pi$ and $\sigma$ are convenient Greek letters. – Omnomnomnom Jul 22 '16 at 12:31
• I would guess that is the case. That makes sense. – Will Jul 22 '16 at 12:36
• Not at all related. The same symbol may have different meanings in the same subject, let alone different subjects. – Kartik Jul 22 '16 at 12:40
• Interestingly, both chemistry and group theory have a notion of "conjugation", which as far as I know is also coincidental. – Ravi Fernando Jul 23 '16 at 17:24

What I knew is that the $\sigma$-bond involves either $sp$, $sp^2$ or $sp^3$ hybridization whereas $\pi$-bond involves overlapping of $p$-orbitals. May refer to LCAO.