Let X and Tx be given.
Assume HTx: topology_on X Tx.
Assume Hnets: ∀N : set, net_pack_in_space X N∃S x : set, subnet_pack_of_in X N S net_pack_converges X Tx S x.
We will prove compact_space X Tx.
We will prove topology_on X Tx ∀Fam : set, open_cover_of X Tx Famhas_finite_subcover X Tx Fam.
Apply andI to the current goal.
An exact proof term for the current goal is HTx.
Let Fam be given.
Assume Hcover: open_cover_of X Tx Fam.
We will prove has_finite_subcover X Tx Fam.
Apply (xm (has_finite_subcover X Tx Fam)) to the current goal.
Assume Hfin: has_finite_subcover X Tx Fam.
An exact proof term for the current goal is Hfin.
Assume Hnofin: ¬ (has_finite_subcover X Tx Fam).
Apply FalseE to the current goal.
We prove the intermediate claim Hexnet: ∃N : set, net_pack_in_space X N (∀S x : set, subnet_pack_of_in X N S¬ (net_pack_converges X Tx S x)).
An exact proof term for the current goal is (open_cover_no_finite_subcover_implies_net_pack_counterexample X Tx Fam HTx Hcover Hnofin).
Apply Hexnet to the current goal.
Let N be given.
Assume Hdata: net_pack_in_space X N (∀S x : set, subnet_pack_of_in X N S¬ (net_pack_converges X Tx S x)).
We prove the intermediate claim HN: net_pack_in_space X N.
An exact proof term for the current goal is (andEL (net_pack_in_space X N) (∀S x : set, subnet_pack_of_in X N S¬ (net_pack_converges X Tx S x)) Hdata).
We prove the intermediate claim Hno: ∀S x : set, subnet_pack_of_in X N S¬ (net_pack_converges X Tx S x).
An exact proof term for the current goal is (andER (net_pack_in_space X N) (∀S x : set, subnet_pack_of_in X N S¬ (net_pack_converges X Tx S x)) Hdata).
We prove the intermediate claim Hexsub: ∃S x : set, subnet_pack_of_in X N S net_pack_converges X Tx S x.
An exact proof term for the current goal is (Hnets N HN).
Apply Hexsub to the current goal.
Let S be given.
Assume Hexx: ∃x : set, subnet_pack_of_in X N S net_pack_converges X Tx S x.
Apply Hexx to the current goal.
Let x be given.
Assume Hsubconv: subnet_pack_of_in X N S net_pack_converges X Tx S x.
We prove the intermediate claim Hsub: subnet_pack_of_in X N S.
An exact proof term for the current goal is (andEL (subnet_pack_of_in X N S) (net_pack_converges X Tx S x) Hsubconv).
We prove the intermediate claim Hconv: net_pack_converges X Tx S x.
An exact proof term for the current goal is (andER (subnet_pack_of_in X N S) (net_pack_converges X Tx S x) Hsubconv).
An exact proof term for the current goal is ((Hno S x Hsub) Hconv).