diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4b074754..f5fb1917 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -93,7 +93,7 @@ When contributing new data (categories, functors, properties, implications), ple
- **Atomic Implications**: Do not add implications that can be deduced from others. For example, do not add "complete => finite products" since it can be deduced from "complete => finitely complete" and "finitely complete => finite products". These are deduced automatically.
-- **No dual implications**: Implications are dualized automatically when applicable. For this reason, adding the category implication "finitely cocomplete => pushouts" is not necessary when "finitely complete => pullbacks" has already been added. Similarly, the functor implication "comonadic => left adjoint" is automatically dualized from "monadic => right adjoint".
+- **No dual implications**: Implications are dualized automatically when applicable. For this reason, adding the category implication "finitely cocomplete => pushouts" is not necessary when "finitely complete => pullbacks" has already been added. Similarly, the functor implication "comonadic => left adjoint" is automatically dualized from "monadic => right adjoint". When an implication can be phrased both in a "limit" or "colimit" variant, prefer the "limit" variant (unless the literature focusses on the "colimit" variant).
- **Relevant implications**: When adding a new property, include implications involving this property and existing properties. For example, when adding the property of categories of having "countable products", also add the implication "countable products => finite products". Refactor existing implications if necessary. Ensure that for most categories and functors, it will be inferred if the property holds or not.
diff --git a/database/data/004_property-assignments/Setne.sql b/database/data/004_property-assignments/Setne.sql
index 783535f2..708543ae 100644
--- a/database/data/004_property-assignments/Setne.sql
+++ b/database/data/004_property-assignments/Setne.sql
@@ -107,12 +107,6 @@ VALUES
FALSE,
'Assume that the sequence of inclusions $\cdots \to \mathbb{N}_{\geq 2} \to \mathbb{N}_{\geq 1} \to \mathbb{N}_{\geq 0} = \mathbb{N}$ as a limit $X$, consisting of maps $X \to \mathbb{N}_{\geq n}$. Since $X$ is non-empty, there is a map $1 \to X$. This corresponds to a family of compatible maps $ 1 \to \mathbb{N}_{\geq n}$, i.e. to compatible elements in $\mathbb{N}_{\geq n}$. But the set $\bigcap_{n \geq 0} \mathbb{N}_{\geq n}$ is empty.'
),
-(
- 'Setne',
- 'coreflexive equalizers',
- FALSE,
- 'The two distinct functions $1 \rightrightarrows \{0,1\}$ have a (unique) common retraction, but they cannot extend to a fork.'
-),
(
'Setne',
'skeletal',
diff --git a/database/data/005_implications/001_limits-colimits-existence-implications.sql b/database/data/005_implications/001_limits-colimits-existence-implications.sql
index 68df0784..03676930 100644
--- a/database/data/005_implications/001_limits-colimits-existence-implications.sql
+++ b/database/data/005_implications/001_limits-colimits-existence-implications.sql
@@ -35,12 +35,19 @@ VALUES
FALSE
),
(
- 'reflexive_coequalizers_are_coequalizers',
- '["coequalizers"]',
- '["reflexive coequalizers"]',
+ 'coreflexive_equalizers_are_equalizers',
+ '["equalizers"]',
+ '["coreflexive equalizers"]',
'This is trivial.',
FALSE
),
+(
+ 'equalizers_via_coreflexive_equalizers',
+ '["coreflexive equalizers", "binary products"]',
+ '["equalizers"]',
+ 'If $f,g : X \rightrightarrows Y$ are two morphisms, we have a coreflexive pair $(\mathrm{id}_X,f), (\mathrm{id}_X,g) : X \rightrightarrows X \times Y$. A morphism with codomain $X$ equalizes $f$ and $g$ if and only if it equalizes $(\mathrm{id}_X,f)$ and $(\mathrm{id}_X,g)$. Thus, their equalizers agree.',
+ FALSE
+),
(
'products_consequence',
'["products"]',
@@ -100,8 +107,8 @@ VALUES
(
'complete_characterization',
'["complete"]',
- '["products", "coreflexive equalizers"]',
- 'See Mac Lane, V.2, Thm. 2. Note that the equalizer appearing the theorem is in fact coreflexive.',
+ '["products", "equalizers"]',
+ 'See Mac Lane, V.2, Thm. 2.',
TRUE
),
(