| Step |
Hyp |
Ref |
Expression |
| 1 |
|
ifpan123g |
|- ( ( if- ( ph , ps , ch ) /\ if- ( ph , th , ta ) ) <-> ( ( ( -. ph \/ ps ) /\ ( ph \/ ch ) ) /\ ( ( -. ph \/ th ) /\ ( ph \/ ta ) ) ) ) |
| 2 |
|
an4 |
|- ( ( ( ( -. ph \/ ps ) /\ ( ph \/ ch ) ) /\ ( ( -. ph \/ th ) /\ ( ph \/ ta ) ) ) <-> ( ( ( -. ph \/ ps ) /\ ( -. ph \/ th ) ) /\ ( ( ph \/ ch ) /\ ( ph \/ ta ) ) ) ) |
| 3 |
|
dfifp4 |
|- ( if- ( ph , ( ps /\ th ) , ( ch /\ ta ) ) <-> ( ( -. ph \/ ( ps /\ th ) ) /\ ( ph \/ ( ch /\ ta ) ) ) ) |
| 4 |
|
ordi |
|- ( ( -. ph \/ ( ps /\ th ) ) <-> ( ( -. ph \/ ps ) /\ ( -. ph \/ th ) ) ) |
| 5 |
|
ordi |
|- ( ( ph \/ ( ch /\ ta ) ) <-> ( ( ph \/ ch ) /\ ( ph \/ ta ) ) ) |
| 6 |
4 5
|
anbi12i |
|- ( ( ( -. ph \/ ( ps /\ th ) ) /\ ( ph \/ ( ch /\ ta ) ) ) <-> ( ( ( -. ph \/ ps ) /\ ( -. ph \/ th ) ) /\ ( ( ph \/ ch ) /\ ( ph \/ ta ) ) ) ) |
| 7 |
3 6
|
bitr2i |
|- ( ( ( ( -. ph \/ ps ) /\ ( -. ph \/ th ) ) /\ ( ( ph \/ ch ) /\ ( ph \/ ta ) ) ) <-> if- ( ph , ( ps /\ th ) , ( ch /\ ta ) ) ) |
| 8 |
1 2 7
|
3bitri |
|- ( ( if- ( ph , ps , ch ) /\ if- ( ph , th , ta ) ) <-> if- ( ph , ( ps /\ th ) , ( ch /\ ta ) ) ) |