The dx1⊗σ3 coefficient of a BPST instanton on the '-slice of R4 where σ3 is the third Pauli matrix . The dx2⊗σ3 coefficient . These coefficients determine the restriction of the BPST instanton A with g=2,ρ=1,z=0 to this slice. The corresponding field strength centered around z=0 . A visual representation of the field strength of a BPST instanton with center z on the compactification S4 of R4 . The BPST instanton is a classical instanton solution to the Yang–Mills equations on R'''4. (en)