Nuprl - Proof: length firstn 1

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At: length firstn 1

1. A : Type
2. A List
3. n : {0...||nil||}

||firstn(n;nil)|| = n

By:	Reduce 3 THEN RecCaseSplit `firstn`

Generated subgoals:

1 3. n : {0...0}
4. 0<n
0 = n
Auto

2 3. n : {0...0}
4. n0
0 = n
Auto

About:

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1	3. n : {0...0} 4. 0<n 0 = n	Auto
2	3. n : {0...0} 4. n0 0 = n	Auto