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+{-# OPTIONS --without-K --safe #-}
+
+open import Categories.Category using (Category)
+open import Category.Dagger.Semiadditive using (IdempotentSemiadditiveDagger)
+open import Level using (Level; suc; _⊔_)
+
+module Category.Dagger.2-Poset {o ℓ e : Level} where
+
+import Categories.Category.Monoidal.Reasoning as ⊗-Reasoning
+
+open import Category.Monoidal.Instance.Posets {ℓ} {e} {e} using (Posets-Monoidal)
+
+open import Categories.Category.Dagger using (HasDagger)
+open import Categories.Category.Helper using (categoryHelper)
+open import Categories.Category.Instance.Posets using (Posets)
+open import Categories.Enriched.Category Posets-Monoidal using () renaming (Category to 2-Poset)
+open import Data.Product using (_,_)
+open import Data.Unit.Polymorphic using (tt)
+open import Relation.Binary using (Poset)
+open import Relation.Binary.Morphism.Bundles using (PosetHomomorphism; mkPosetHomo)
+
+open PosetHomomorphism using (⟦_⟧; cong)
+
+record Dagger-2-Poset : Set (suc (o ⊔ ℓ ⊔ e)) where
+
+  open Poset using (Carrier; _≈_; isEquivalence)
+
+  field
+    2-poset : 2-Poset o
+
+  open 2-Poset 2-poset
+
+  category : Category o ℓ e
+  category = categoryHelper record
+      { Obj = Obj
+      ; _⇒_ = λ A B → Carrier (hom A B)
+      ; _≈_ = λ {A B} → _≈_ (hom A B)
+      ; id = ⟦ id ⟧ tt
+      ; _∘_ = λ f g → ⟦ ⊚ ⟧ (f , g)
+      ; assoc = ⊚-assoc
+      ; identityˡ = unitˡ
+      ; identityʳ = unitʳ
+      ; equiv = λ {A B} → isEquivalence (hom A B)
+      ; ∘-resp-≈ = λ f≈h g≈i → cong ⊚ (f≈h , g≈i)
+      }
+
+  field
+    hasDagger : HasDagger category
+
+  private
+    module P {A B : Obj} = Poset (hom A B)
+
+  open P using (_≤_) public
+  open Category category using (_⇒_) public
+  open HasDagger hasDagger using (_†) public
+
+  field
+    †-resp-≤ : {A B : Obj} {f g : A ⇒ B} → f ≤ g → f † ≤ g †
+
+dagger-2-poset : {𝒞 : Category o ℓ e} (ISA† : IdempotentSemiadditiveDagger 𝒞) → Dagger-2-Poset
+dagger-2-poset {𝒞} ISA† = record
+    { 2-poset = record
+        { Obj = Obj
+        ; hom = λ A B → record
+            { Carrier = A ⇒ B
+            ; _≈_ = _≈_
+            ; _≤_ = ISA†._≤_
+            ; isPartialOrder = record
+                { isPreorder = record
+                    { isEquivalence = equiv
+                    ; reflexive = λ x≈y → Equiv.trans (ISA†.+-congʳ x≈y) ISA†.≤-refl
+                    ; trans = ISA†.≤-trans
+                    }
+                ; antisym = ISA†.≤-antisym
+                }
+            }
+        ; id = mkPosetHomo _ _ (λ _ → id) (λ _ → ISA†.≤-refl)
+        ; ⊚ = mkPosetHomo _ _ (λ (f , g) → f ∘ g) (λ (≤₁ , ≤₂) → ISA†.≤-resp-∘ ≤₁ ≤₂)
+        ; ⊚-assoc = assoc
+        ; unitˡ = identityˡ
+        ; unitʳ = identityʳ
+        }
+    ; hasDagger = record
+        { _† = ISA†._†
+        ; †-identity = ISA†.†-identity
+        ; †-homomorphism = ISA†.†-homomorphism
+        ; †-resp-≈ = ISA†.⟨_⟩†
+        ; †-involutive = ISA†.†-involutive
+        }
+    ; †-resp-≤ = ISA†.†-resp-≤
+    }
+  where
+    module ISA† = IdempotentSemiadditiveDagger ISA†
+    open Category 𝒞
+    open ⊗-Reasoning ISA†.+-monoidal