IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
select concat2 1. T : Type
2. (T List) List
3. u : T List
4. v : (T List) List
5. n:||concat(v)||.
5. m:||v||.
5. ||concat(firstn(m;v))||n 5. & n-||concat(firstn(m;v))||<||v[m]||
5. & concat(v)[n] = v[m][(n-||concat(firstn(m;v))||)]
n:||concat([u / v])||.
m:||[u / v]||.
||concat(firstn(m;[u / v]))||n & n-||concat(firstn(m;[u / v]))||<||[u / v][m]||
& concat([u / v])[n] = [u / v][m][(n-||concat(firstn(m;[u / v]))||)]
By:
Unfold `concat` 0 THEN Reduce 0 THEN Try (Fold `concat` 0)