theorem zip01 (l: nat): $ zip 0 l = 0 $;
Step | Hyp | Ref | Expression |
---|---|---|---|
1 |
len (zip 0 l) = 0 <-> zip 0 l = 0 |
||
3 |
len (zip 0 l) = min (len 0) (len l) |
||
7 |
len 0 = 0 |
||
8 |
min (len 0) (len l) = min 0 (len l) |
||
11 |
0 <= len l |
||
12 |
min 0 (len l) = 0 |
||
13 |
eqtr* |
min (len 0) (len l) = 0 |
|
14 |
eqtr* |
len (zip 0 l) = 0 |
|
15 |
zip 0 l = 0 |