wiki_research

personal research wiki
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commit 0fc6762b6c647c7c9ba0931cb53026006d293953
parent 43c75415d4d0582cd020996757bc6ae2c8fd12b0
Author: Antoine Amarilli <a3nm@a3nm.net>
Date:   Sun, 12 Jan 2025 00:46:40 +0100

commit with codex

Diffstat:
automata_symmetric | 2++
composition | 6++++++
connected_component | 7+++++++
forest | 2++
graph | 94+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
graph_modification_treewidth | 5+++++
graph_theorem | 7+++++++
graph_theory | 2++
level_ancestor | 10++++++++++
mathematics | 3+++
out_tree | 5+++++
relation_mathematics | 13+++++++++++++
strong_connectivity_augmentation | 12++++++++++++
strongly_connected_component | 2+-
transitivity | 2++
tree | 3+++
tree_balancing | 14++++++++++++++
tree_decomposition_updating | 6++++++
treewidth | 45+++++++++++++++++++++++++++++++++++++++++++++
treewidth_practical | 7-------
20 files changed, 239 insertions(+), 8 deletions(-)

diff --git a/automata_symmetric b/automata_symmetric @@ -8,3 +8,5 @@ Studied in [kutrib2022finite] in a [deterministic] and [nondeterministic] settin See also: [automata_reversible], [turing_machine_symmetric] Up: [automata] + +Aliases: symmetric automata diff --git a/composition b/composition @@ -0,0 +1,6 @@ +# Composition + +- [composition_law] +- [function_composition] + +Up: [mathematics] diff --git a/connected_component b/connected_component @@ -0,0 +1,7 @@ +# Connected component + +An [equivalence_class] of the [reachability] [equivalence_relation] in an [undirected_graph] + +See also: [strongly_connected_component] + +Up: [graph_basic_notions] diff --git a/forest b/forest @@ -5,3 +5,5 @@ A [set] of [trees] (for [tree_unordered]), or possibly a [sequence] of [trees] ( Generalization: [pseudoforest] Up: [data_structure] + +Aliases: forests diff --git a/graph b/graph @@ -0,0 +1,94 @@ +# Graph + +[graph_definition] + +## Basic notions + +See [graph_basic_notions] + +## Advanced notions + +- [graph_minor] + - [robertson_seymour] + +## Types + +- [graph_undirected] or [graph_directed] +- [graph_weighted] + - [graph_weighted_regimes]: question of how weights are encoded + - e.g., [unary] or [binary] +- [multigraph] + +## [Graph_tractability] + +- [width_measure] +- [graph_decomposition] + +## [theorems] + +- [graph_theorem] + +## Results + +- [handshaking_lemma], consequence of [degree_sum_formula] +- [graph_removal_lemma] + +## [graph_algorithm] + +- [floyd_warshall] +- [bellman_ford] +- [dijkstras_algorithm] + +## [graph_family] + +See [graph_family] + +## [graph_problem] + +See [graph_problem] + +## Fields + +- [graph_theory] + - [pursuit_evasion] + - [extremal_graph_theory] + +## Constructions + +- [cayley_graph] +- [line_graph] +- [dual_graph] +- [incidence_graph] +- [graph_complementation] + +## [graph_operations] + +- [graph_union] +- [graph_product] +- [edge_contraction] + +## Software + +[graph_software] + +## Problems + +- [minimum_linear_arrangement] +- [graph_sandwich_problem] +- [planarity_testing] + +## Graph representations + +- [adjacency_list] +- [adjacency_matrix] + +## Generalizations + +- [hypergraph] +- [multigraph] + +See also: [graph_database], [graph_theory], [graph_query_languages], [game_on_graph] + +Up: [data_structure], [computer_science] + +Aliases: graphs diff --git a/graph_modification_treewidth b/graph_modification_treewidth @@ -0,0 +1,5 @@ +# Graph modification treewidth + +- reducing [treewidth] by removing [graph] [edges]: [marchand2022tree] + +Up: [treewidth], [graph_modification] diff --git a/graph_theorem b/graph_theorem @@ -0,0 +1,7 @@ +# Graph theorem + +- [graph_structure_theorem] +- [four_color_theorem] +- [strong_perfect_graph_theorem] + +Up: [graph] diff --git a/graph_theory b/graph_theory @@ -2,5 +2,7 @@ - [friendship_theorem] - [handshaking_lemma] +- [pursuit_evasion] +- [extremal_graph_theory] Up: [theoretical_computer_science] on [graph] diff --git a/level_ancestor b/level_ancestor @@ -0,0 +1,10 @@ +# Level ancestor + +Do [preprocessing] on [tree] and compute [data_structure] such that given a [node] and integer d you can find the [ancestor] of the [node] at distance d from it (or, equivalently, at specified [depth]) + +Can be done with linear preprocessing of the tree and constant query time +- cf for instance [bender2004level] +- [alstrup2000improved] for [trees] under [updates], and to find the node with minimum weight on the path between two nodes when the tree is weighted +- [bender2003level]: simplified version of the problem (decompose into [microtrees]) + +Up: [data_structure] diff --git a/mathematics b/mathematics @@ -34,6 +34,7 @@ - [cartesian_product] - [plane_mathematics] - [modulo] +- [relation_mathematics] ## Notions @@ -50,6 +51,8 @@ - [equality] - [inequality_mathematics] - [disequality] +- [symmetry] +- [composition] ## Fields diff --git a/out_tree b/out_tree @@ -0,0 +1,5 @@ +# Out tree + +A [directed_graph] whose underlying [undirected_graph] is a [tree_unrooted] and all [edges] are pointing towards the [leaves] + +Up: [tree] diff --git a/relation_mathematics b/relation_mathematics @@ -0,0 +1,13 @@ +# Relation (mathematics) + +A relation on a set X is a subset of X times X ([cartesian_product]) + +- [relation_symmetric] +- [relation_reflexive] +- [relation_transitive] + +Up: [mathematics] + +See also: [graph_directed], [composition_law] + +Aliases: mathematics relation diff --git a/strong_connectivity_augmentation b/strong_connectivity_augmentation @@ -0,0 +1,12 @@ +# Strong connectivity augmentation + +https://en.wikipedia.org/wiki/Strong_connectivity_augmentation + +minimal number of [edges] to add to make a [directed_graph] [strongly_connected] + +- can be solved in [linear_time] in the unweighted setting +- [NP_complete] in the setting of [weighted_graphs] + +cf [raghavan2005note] + +Up: [strongly_connected_component], [graph_modification] diff --git a/strongly_connected_component b/strongly_connected_component @@ -9,4 +9,4 @@ Up: [graph] See also: [biconnected_component], [connected_component], [strongly_connected] -Aliases: SCC +Aliases: SCC, strongly connected components diff --git a/transitivity b/transitivity @@ -4,3 +4,5 @@ - [transitive_closure] Up: [mathematics] + +See also: [relation_transitive] diff --git a/tree b/tree @@ -19,6 +19,7 @@ - [tree_binary_full] - [tree_rooted] - [tree_unrooted] +- [tree_balanced] - [path] - [downward_path] @@ -50,6 +51,8 @@ ## Related notions and application cases in [TCS] +- [heap] +- [binary_search_tree] - [tree_automaton] - [range_tree] - [tree_decomposition] diff --git a/tree_balancing b/tree_balancing @@ -0,0 +1,14 @@ +# Tree balancing + +Ensure that [tree] is [tree_balanced], and maintain it upon changes to the tree + +[Data_structures]: + +- [avl_tree] +- [red_black_tree] +- [splay_tree] +- [top_tree] + +See also: [avl_tree], [binary_search_tree] + +Up: [trees] diff --git a/tree_decomposition_updating b/tree_decomposition_updating @@ -0,0 +1,6 @@ +# Updating tree decomposition + +- [korhonen2023dynamic] +- [gottlob2022incremental], sur [generalized_hypertree_decomposition] + +Up: [incremental_maintenance] of [tree_decomposition] diff --git a/treewidth b/treewidth @@ -0,0 +1,45 @@ +# Treewidth + +A [width_measure] on [graphs] + +[treewidth_definition] + +## Small values + +- [Graphs] of treewidth 1 are precisely [forests], including [trees] +- [treewidth_2] + +## Variants + +- [hypertreewidth] +- [submodular_width] + +## Related notions + +- [grid_minor] +- [bramble] +- [contraction] never makes treewidth increase + +## Generalizations and related problems + +- [tree_decomposition_updating] +- [semantic_treewidth] for [queries] +- [graph_modification_treewidth] +- [treewidth_directed] + +## [Computational_problem] + +- [Treewidth_computation] +- [Treewidth_approximation] + +## Applications in [TCS] + +- [bidimensionality] + +## Practical applications + +[treewidth_practical] + +Up: [width_measure] + +See also: [courcelle_theorem], [treelike_data], [message_passing], [pursuit_evasion], [elimination_order], [obstruction] diff --git a/treewidth_practical b/treewidth_practical @@ -1,7 +0,0 @@ -# Treewidth practical - -- [senellart], [silviu]: [silviu2019experimental] -- [marx2020four] -- practical works such as [goharshady2020efficient] - -Up: [treewidth]