wiki_research

commit edf92ca8c40012c91db219066984361f2f84b42d
parent 12d718341c043071c15e707113db981e68b69290
Author: Antoine Amarilli <a3nm@a3nm.net>
Date:   Mon, 16 Feb 2026 22:48:37 +0100

Merge remote-tracking branch 'origin/master'

Diffstat:
disjoint_union
 | 
2
++
graph_basic_notions
 | 
1
+
graph_empty
 | 
9
+++++++++
graph_family
 | 
3
++-
graph_p5_free
 | 
2
++
graph_pk_free
 | 
8
++++----
independent_set
 | 
2
+-
matrix
 | 
4
++++
matrix_probabilistic
 | 
7
+++++++
matrix_types
 | 
2
++
submatrix
 | 
4
++--

11 files changed, 36 insertions(+), 8 deletions(-)
diff --git a/disjoint_union b/disjoint_union
@@ -2,6 +2,8 @@
 
 The [union] of two [sets] that are [disjoint]
 
+- [graph_disjoint_union]
+
 Up: [union]
 
 Aliases: disjoint unions
diff --git a/graph_basic_notions b/graph_basic_notions
@@ -34,6 +34,7 @@
   - [incidence_graph]
 - [balanced_separator]
 - [graph_product]
+- [graph_empty]
 
 Up: [graph]
 
diff --git a/graph_empty b/graph_empty
@@ -0,0 +1,9 @@
+# Graph empty
+
+A [graph] with no [edges], or sometimes the graph with no [edges] and no [vertices]
+
+Up: [graph_basic_notions]
+
+Aliases: empty graph
+
+See also: [independent_set], [single_vertex_graph]
diff --git a/graph_family b/graph_family
@@ -29,7 +29,8 @@ A (generally [infinite]) set of [graphs]
 - [graph_free]
   - [graph_h_free]
   - [graph_induced_h_free]
-    - [graph_pk_free]
+    - [Pk_free_graphs]
+      - [P4_free_graphs]
   - [graph_h_minor_free]
 
 - [graph_sparse]
diff --git a/graph_p5_free b/graph_p5_free
@@ -5,3 +5,5 @@ https://www.graphclasses.org/classes/gc_396.html
 cf, e.g., [chudnowski2023cops]
 
 Up: [graph_pk_free]
+
+Aliases: P5 free graph, P5 free graphs
diff --git a/graph_pk_free b/graph_pk_free
@@ -2,14 +2,14 @@
 
 An [undirected_graph] is *P_k-free* if it does not have an [induced_subgraph] which is [graph_isomorphic] to a [path] on k [vertices]
 
-- P_2-free means no [edge] at all, so [graph_empty], or [independent_set]
+- P_2-free means no [edge] at all, so [empty_graph], or [independent_set]
 - P_3-free means every [connected_component] is a [clique]
   - https://math.stackexchange.com/questions/3564039/describe-all-graphs-that-do-not-contain-p-3-as-an-induced-subgraph
-- P_4-free are precisely the [cographs]
-- P_5-free: [graph_p5_free]
+- [P4_free_graphs] are precisely the [cographs]
+- [P5_free_graphs]
 
 Up: [graph_family], [graph_h_free]
 
-Aliases: PK free graph
+Aliases: PK free graph, PK free graphs
 
 See also: [forbidden_minor]
diff --git a/independent_set b/independent_set
@@ -26,7 +26,7 @@ An *independent set* is a [subset] of [vertices] of an [undirected_graph] such t
 [fractional_independent_set]
 - like [fractional_edge_cover] vs [edge_cover]
 
-See also: [matching], [vertex_cover]
+See also: [matching], [vertex_cover], [empty_graph]
 
 Up: [graph_substructure]
 
diff --git a/matrix b/matrix
@@ -18,6 +18,10 @@
 ## Concepts
 
 - [eigenvalue]
+- [cell]
+- [row]
+- [column]
+- [submatrix]
 
 ## [computational_problem]
 
diff --git a/matrix_probabilistic b/matrix_probabilistic
@@ -0,0 +1,7 @@
+# Matrix probabilistic
+
+A [matrix] where each [cell] contains a [probability], i.e., a [number] between 0 and 1
+
+Up: [matrix_types]
+
+Aliases: probabilistic matrix, probabilistic matrices
diff --git a/matrix_types b/matrix_types
@@ -20,5 +20,7 @@
 - [pet_matrix]
 - [matrix_symmetric]
 - [matrix_balanced]
+- [matrix_stochastic]
+- [matrix_probabilistic]
 
 Up: [matrix]
diff --git a/submatrix b/submatrix
@@ -1,7 +1,7 @@
 # Submatrix
 
-A [matrix] obtained from another [matrix] by deleting rows and columns
+A [matrix] obtained from another [matrix] by deleting [rows] and [columns]
 
 Up: [matrix]
 
-See also: [subsequence]
+See also: [subsequence], [block_submatrix]