Ramsey Game Claim . Any coloring of the edges of the complete graph on 6 vertices with 2 colors contains a monochromatic triangle. Every vertex is incident to at least 3 edges of the same color, say red.
Ramsey Game Claim . Any coloring of the edges of the complete graph on 6 vertices with 2 colors contains a monochromatic triangle. Every vertex is incident to at least 3 edges of the same color, say red.
Ramsey Game Claim . Any coloring of the edges of the complete graph on 6 vertices with 2 colors contains a monochromatic triangle. Every vertex is incident to at least 3 edges of the same color, say red. If two of the three neighbours of that vertex are linked by a red edge, then a red triangle arises.
Ramsey Game Claim . Any coloring of the edges of the complete graph on 6 vertices with 2 colors contains a monochromatic triangle. Every vertex is incident to at least 3 edges of the same color, say red. If two of the three neighbours of that vertex are linked by a red edge, then a red triangle arises. Otherwise, these three neighbours create a blue tringle.
Ramsey Theory Ramsey's theorem states that one will find big monochromatic cliques in any edge colouring of a sufficiently large complete graph.
Ramsey Theory Ramsey's theorem states that one will find big monochromatic cliques in any edge colouring of a sufficiently large complete graph. Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one will find big monochromatic cliques in any edge colouring of a sufficiently large complete graph. Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory and Data Mining “Ramsey theory predicts that more elaborate patterns will emerge as the number of data points increases”.
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one will find big monochromatic cliques in any edge colouring of a sufficiently large complete graph. Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one Ramsey will find big monochromatic cliques in numbers : any edge colouring of a sufficiently R(3,3)=6 large complete graph. Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one Ramsey will find big monochromatic cliques in numbers : any edge colouring of a sufficiently R(3,3)=6 large complete graph. R(4,4)=18 Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one Ramsey will find big monochromatic cliques in numbers : any edge colouring of a sufficiently R(3,3)=6 large complete graph. R(4,4)=18 R(5,5)=? Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one Ramsey will find big monochromatic cliques in numbers : any edge colouring of a sufficiently R(3,3)=6 large complete graph. R(4,4)=18 42< R(5,5)<50 Frank P. Ramsey 22 February Born 1903 Cambridge 19 January 1930 Died (aged 26)
Ramsey Theory Ramsey theory is a branch of mathematics that studies the conditions under which order must appear. Ramsey's theorem states that one Ramsey will find big monochromatic cliques in numbers : any edge colouring of a sufficiently R(3,3)=6 large complete graph. R(4,4)=18 42< R(5,5)<50 Erdős asks us to imagine an alien force, vastly more powerful than us, landing on Earth and demanding the value of R(5, 5) or they will destroy our planet. In that case, he claims, we should marshal all our Frank P. Ramsey computers and all our mathematicians and attempt 22 February to find the value. But suppose, instead, that they Born 1903 ask for R(6, 6). In that case, he believes, we should Cambridge 19 January 1930 attempt to destroy the aliens. Died (aged 26)
Paul Erdős Paul Erdős was a Hungarian mathematician. He was one of the most prolific mathematicians of the 20th century. Erdős pursued problems in combinatorics, graph theory, number theory, classical analysis, approximation theory, set theory, and probability theory. 26 March Born 1913 20 Sept. Died 1996 (aged 83)
Collaboration graph vertices are people • edges connect people who collaborate • (e.g. have a joint publication) Collaboration distance is the length of a shortest path between two people in the collaboration graph
Collaboration graph vertices are people • edges connect people who collaborate • (e.g. have a joint publication) Collaboration distance is the length of a shortest path between two people in the collaboration graph The Erdős number is the distance to Paul Erdős .
Shortest Path
Shortest Path Problem . Find a shortest path between two vertices in a graph
Shortest Path Problem . Find a shortest path between two vertices in a graph Applications : navigation, routing protocols
Shortest Path Problem . Find a shortest path between two vertices in a graph Edsger Wybe Dijkstra Applications : navigation, routing protocols Born 11 May 1930 Rotterdam, Netherlands Dijkstra’s Algorithm Died 6 August 2002 (aged 72) Nuenen, Netherland
Did you know that The difference in the speed of clocks at different heights above the earth is now of considerable practical importance, with the advent of very accurate navigation systems based on signals from satellites. If one ignored the predictions of general relativity theory, the position that one calculated would be wrong by several miles! Stephen Hawking A brief history of time
My Small World Alain Vladimir Hertz Deineko Vadim Lozin
My Small World Alain Vladimir Hertz Deineko Vadim Lozin Kathie Cameron Horst Sachs Paul Erdős
Marriage Problem: • There are n boys and n girls. • For each pair, it is either compatible or not. Goal: find the maximum number of compatible pairs.
Marriage Problem: • There are n boys and n girls. • For each pair, it is either compatible or not. Goal: find the maximum number of compatible pairs. Bipartite graph
Marriage Problem: • There are n boys and n girls. • For each pair, it is either compatible or not. Goal: find the maximum number of compatible pairs. Bipartite graph Definition. A matching in a graph is a subset of its edges no two of which share a vertex.
Marriage Problem: • There are n boys and n girls. • For each pair, it is either compatible or not. Goal: find the maximum number of compatible pairs. Bipartite graph Definition. A matching in a graph is a subset of its edges no two of which share a vertex.
The maximum matching problem Problem : Find a matching of maximum size Bipartite graph Definition. A matching in a graph is a subset of its edges no two of which share a vertex.
The maximum matching problem Problem : Find a matching of maximum size Bipartite graph Maximum Flow Definition. A matching in a graph is a subset of its edges no two of which share a vertex.
The maximum matching problem Problem : Find a matching of maximum size Definition. A matching in a graph is a subset of its edges no two of which share a vertex.
The maximum matching problem Problem : Find a matching of maximum size The matching algorithm by Edmonds is one of the most involved of Definition. A matching in a graph is a subset combinatorial of its edges no two of which share a vertex. algorithms.
Stable Matching problem Stable Marriage problem Given n men and n women, where each person has ranked all members of the opposite sex in order of preference, marry the men and women together such that there are no two people of opposite sex who would both rather have each other than their current partners. When there are no such pairs of people, the set of marriages is deemed stable.
Stable Matching problem Stable Marriage problem Given n men and n women, where each person has ranked all members of the opposite sex in order of preference, marry the men and women together such that there are no two people of opposite sex who would both rather have each other than their current partners. When there are no such pairs of people, the set of marriages is deemed stable. In 1962, David Gale and Lloyd Shapley proved that, for any equal number of men and women, it is always possible to solve the SMP and make all marriages stable. They presented an algorithm to do so.
Stable Matching problem Stable Marriage problem Given n men and n women, where each person has ranked all members of the opposite sex in order of preference, marry the men and women together such that there are no two people of opposite sex who would both rather have each other than their current partners. When there are no such pairs of people, the set of marriages is deemed stable. Algorithms for finding solutions In 1962, David Gale and Lloyd Shapley to the stable marriage problem proved that, for any equal number of have applications in a variety of men and women, it is always possible real-world situations, perhaps to solve the SMP and make all the best known of these being marriages stable. They presented an in the assignment of graduating algorithm to do so. medical students to their first hospital appointments.
Stable Matching problem Stable Marriage problem
My Small World Alain Vladimir Hertz Deineko Vadim Lozin Kathie Cameron Horst Sachs Paul Erdős
My Small World Alain Vladimir Hertz Deineko Vadim Irina Lozin Lozina Kathie Cameron Horst Sachs Paul Erdős
Logical Analysis of Data
Logical Analysis of Data Peter Hammer
Logical Analysis of Data Peter Hammer Hammer founded the Rutgers University Center for Operations Research, and created and edited the journals Discrete Mathematics, Discrete Applied Mathematics, Discrete Optimization, Annals of Discrete Mathematics, Annals of Operations Research, and SIAM Monographs on Discrete Mathematics and Applications
Logical Analysis of Data He contributed to the fields of operations research and applied discrete mathematics through the study of pseudo- Boolean functions and their connections to graph theory and data mining. Peter Hammer Hammer founded the Rutgers University Center for Operations Research, and created and edited the journals Discrete Mathematics, Discrete Applied Mathematics, Discrete Optimization, Annals of Discrete Mathematics, Annals of Operations Research, and SIAM Monographs on Discrete Mathematics and Applications
Pseudo-Boolean optimization
Pseudo-Boolean optimization Definition. A pseudo-Boolean function is a f ( x , x , , x ) 1 2 n real-valued function with Boolean variables.
Pseudo-Boolean optimization Definition. A pseudo-Boolean function is a f ( x , x , , x ) 1 2 n real-valued function with Boolean variables. • each variable x i can take only two possible values 0 or 1 • can take any real value f ( x , x , , x ) 1 2 n
Pseudo-Boolean optimization Definition. A pseudo-Boolean function is a f ( x , x , , x ) 1 2 n real-valued function with Boolean variables. • each variable x i can take only two possible values 0 or 1 • can take any real value f ( x , x , , x ) 1 2 n f xz 5 x 11 x y 7 xy 3 y z 3
Pseudo-Boolean optimization Definition. A pseudo-Boolean function is a f ( x , x , , x ) 1 2 n real-valued function with Boolean variables. • each variable x i can take only two possible values 0 or 1 • can take any real value f ( x , x , , x ) 1 2 n f xz 5 x 11 x y 7 xy 3 y z 3 1 x x
Pseudo-Boolean maximization f xz 5 x 11 x y 7 xy 3 y z 3
Pseudo-Boolean maximization 1 f xz 5 x 11 x y 7 xy 3 y z 3 x x
Pseudo-Boolean maximization 1 f xz 5 x 11 x y 7 xy 3 y z 3 x x xz 5 x 11 x y 7 xy 3 y z 2
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