Description: If a natural number is even, its successor is odd. (Contributed by Mario Carneiro, 16-Nov-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | nnneo | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nnon | |
|
2 | onnbtwn | |
|
3 | 1 2 | syl | |
4 | 3 | 3ad2ant1 | |
5 | suceq | |
|
6 | 5 | eqeq1d | |
7 | 6 | 3ad2ant3 | |
8 | ovex | |
|
9 | 8 | sucid | |
10 | eleq2 | |
|
11 | 9 10 | mpbii | |
12 | 2onn | |
|
13 | nnmord | |
|
14 | 12 13 | mp3an3 | |
15 | simpl | |
|
16 | 14 15 | syl6bir | |
17 | 11 16 | syl5 | |
18 | simpr | |
|
19 | nnmcl | |
|
20 | 12 19 | mpan | |
21 | nnon | |
|
22 | oa1suc | |
|
23 | 20 21 22 | 3syl | |
24 | 1oex | |
|
25 | 24 | sucid | |
26 | df-2o | |
|
27 | 25 26 | eleqtrri | |
28 | 1onn | |
|
29 | nnaord | |
|
30 | 28 12 20 29 | mp3an12i | |
31 | 27 30 | mpbii | |
32 | nnmsuc | |
|
33 | 12 32 | mpan | |
34 | 31 33 | eleqtrrd | |
35 | 23 34 | eqeltrrd | |
36 | 35 | ad2antrr | |
37 | 18 36 | eqeltrrd | |
38 | peano2 | |
|
39 | nnmord | |
|
40 | 12 39 | mp3an3 | |
41 | 38 40 | sylan2 | |
42 | 41 | ancoms | |
43 | 42 | adantr | |
44 | 37 43 | mpbird | |
45 | 44 | simpld | |
46 | 45 | ex | |
47 | 17 46 | jcad | |
48 | 47 | 3adant3 | |
49 | 7 48 | sylbid | |
50 | 4 49 | mtod | |