MathOverflow

In formal logic and proof theory we often study different axiomatic systems for the sake of it. It is considered interesting to see what theorems and derivations one can prove. One can attempt to ascribe certain kinds of meanings to the symbols, too...

I recently came across the following in something I'm working on, and I'd never seen it before. Consider\begin{align*}f_1(x) &= (1+x)^{1/1} \\\f_2(x) &= (1+x)^{2/1} (1+2x)^{-1/2} \\\f_3(x) &= (1+x)^{3/1} (1+2x)^{-3/2} (1+3x)^{1/3} \\\f_4...

It is ''well-known'' that the third stable homotopy group of spheres is cyclic of order $24$. It is also ''well-known'' that the quaternionic Hopf map $\nu:S^7 \to S^4$, an $S^3$-bundle, suspends to a generator of $\pi_8 (S^5)=\pi_{3}^{st}$. It is even...

Cross-posted to MSE where it received 2 upvotes but no answers.
I am looking for a reasonably nice exact unitary model of the faithful 6-dimensional complex representation of the Schur cover $6.A_7$.
The ATLAS gives characteristic-zero generators for the representation labeled something like$$6.A_7,\qquad 6(a),\qquad \dim=6,$$over a small algebraic field, essentially$$K=\mathbb Q(\sqrt{2},\zeta_3).$$...