as,bs:T List, i:
||as||. (as @ bs)[i] = as[i]a:T, as:T List, i:
. i
0 
(a.as)[i] = aa:T, as:T List, i:. 0<i i||as|| (a.as)[i] = as[(i-1)]| Theorem | Name |
| as,bs:T List, i:||as||. (as @ bs)[i] = as[i] | [select_append_front] |
| cites the following: | |
| a:T, as:T List, i:. i0 (a.as)[i] = a | [select_cons_hd] |
| a:T, as:T List, i:. 0<i i||as|| (a.as)[i] = as[(i-1)] | [select_cons_tl] |