User blog comment:Deedlit11/Ordinal Notations VI: Up to a weakly compact cardinal/@comment-30004975-20180129211630/@comment-5529393-20180130074901

I(1,0) is \(\Psi_{\Xi(2,0)}(1,\Xi(2,0))\). Since you can't access \(\Xi(2,0)\) yet at (0,0), we can't construct I(1,0) yet, so \(\Psi_{I(1,0)}(0,0)\) is just I(1,0). On the other hand, \(\Psi_{\Psi_{\Xi(2,0)}(1,\Xi(2,0))}(0,2)\) should collapse normally.