Take spin-1/2 Pauli operators acting on a site j of a 1D chain, σ σ j + , σ σ j − − , σ σ j z . Taking the anticommutator of σ σ j + and σ σ j − − , we find { σ σ j + , σ σ j − − } = I , as would be expected from fermionic creation and annihilation operators. We might then be tempted to set