actualize store with page by morphism :store → file-content; :elem → nat; :data → buffer; ∅ → ∅; [ ] → [ ]; # → #; -- → --; ∈ → ∈; ⊆ → ⊆; st → content; st0 → content0; st1 → content1; st2 → content2; a → n2; b → n3; c → n4; d → buf; d0 → buf0; d1 → buf1; d2 → buf2; [ ] → [ ] end actualize