Metamath Proof Explorer


Theorem catstr

Description: A category structure is a structure. (Contributed by Mario Carneiro, 3-Jan-2017)

Ref Expression
Assertion catstr Base ndx U Hom ndx H comp ndx · ˙ Struct 1 15

Proof

Step Hyp Ref Expression
1 1nn 1
2 basendx Base ndx = 1
3 4nn0 4 0
4 1nn0 1 0
5 1lt10 1 < 10
6 1 3 4 5 declti 1 < 14
7 4nn 4
8 4 7 decnncl 14
9 homndx Hom ndx = 14
10 5nn 5
11 4lt5 4 < 5
12 4 3 10 11 declt 14 < 15
13 4 10 decnncl 15
14 ccondx comp ndx = 15
15 1 2 6 8 9 12 13 14 strle3 Base ndx U Hom ndx H comp ndx · ˙ Struct 1 15