definition lpx_sn_alt: relation3 lenv term term → relation lenv ≝
λR,L1,L2. |L1| = |L2| ∧
(∀I1,I2,K1,K2,V1,V2,i.
- â\87©[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â\87©[i] L2 ≡ K2.ⓑ{I2}V2 →
+ â¬\87[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â¬\87[i] L2 ≡ K2.ⓑ{I2}V2 →
I1 = I2 ∧ R K1 V1 V2
).
lemma lpx_sn_intro_alt: ∀R,L1,L2. |L1| = |L2| →
(∀I1,I2,K1,K2,V1,V2,i.
- â\87©[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â\87©[i] L2 ≡ K2.ⓑ{I2}V2 →
+ â¬\87[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â¬\87[i] L2 ≡ K2.ⓑ{I2}V2 →
I1 = I2 ∧ R K1 V1 V2
) → lpx_sn R L1 L2.
/4 width=4 by lpx_sn_alt_inv_lpx_sn, conj/ qed.
lemma lpx_sn_inv_alt: ∀R,L1,L2. lpx_sn R L1 L2 →
|L1| = |L2| ∧
∀I1,I2,K1,K2,V1,V2,i.
- â\87©[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â\87©[i] L2 ≡ K2.ⓑ{I2}V2 →
+ â¬\87[i] L1 â\89¡ K1.â\93\91{I1}V1 â\86\92 â¬\87[i] L2 ≡ K2.ⓑ{I2}V2 →
I1 = I2 ∧ R K1 V1 V2.
#R #L1 #L2 #H lapply (lpx_sn_lpx_sn_alt … H) -H
#H elim H -H /3 width=4 by conj/