Flashcards
Combinatorics

Cards in this deck (52)
- 1Ramsey Number definition.

- 2R(3,3) = 6 proof.

- 3R(1,t) = 1 proof.

- 4R(2,t) = t proof.

- 5R(s,t) exists, then R(t,s) = R(s,t) proof.

- 6State Erdos and Szekeres theorem.

- 7Erdos and Szekeres theorem: R(s,t) <= R(s-1,t) + R(s,t-1) proof.

- 8R(s,t) <= (s+t-2 C s-1), R(t,t) <= (2t-1 C t-1) < 2^(2t-2) proof.

- 9R(t) <- 2^(2t-1) proof.

- 10Ramsey Number of s1,..,sk definition.

- 11Rk(s1,....,sk) exists proof.

- 12R(3,4) = 9 proof.

- 13State Erdos theorem.

- 14Erdos: (n C t) * 2^(1 - (t C 2)) < 1 then R(t) > n proof.

- 15t>= 4 then R(t) > floor( 2^(t/2) ) holds proof.

- 16State Ramsey number for sets.

- 17R^(r)(s,t) <= R^(r-1)[R^(r)(s-1,t), R^(r)(s,t-1)] + 1 proof.
![R^(r)(s,t) <= R^(r-1)[R^(r)(s-1,t), R^(r)(s,t-1)] + 1 proof.](https://examtimeassets.s3.amazonaws.com/uploads/media/image/49594123/desktop_dd8ea7b5-a60d-49c7-806d-e1bda3a6f9ea.png)
- 18State Schur theorem.

- 19Schur theorem x+y=z proof.

- 20Any sequence of a1,...,an, n>st contains an increasing subsequence of length s+1 or a decreasing subsequence of t+1 proof.

- 21Van der Waerden number definition.

- 22Positional, strong, maker-breaker, breaker-maker game definition.

- 23Strategy definition.

- 24Winning strategy for Breaker in maker-breaker game then S is a drawing strategy for P2 in the strong game proof.

- 25Zermelo theorem.

- 26There is no winning strategy for P2 in the strong game proof.

- 27If maker has a winning strategy in breaker-maker game then ...

- 28Two statements that are true in a game.

- 29Every red-blue-colouring of X yields a mono A in F. The P1 has a winning strategy for the strong game, moreover, maker has a winning strategy for the maker-breaker game proof.

- 30Erdos-Selfridge theorem.

- 31Erdos-Selfridge theorem for breaker-maker game.

- 32Pairing strategy definition.

- 33The mxm n-in-a-row maker-breaker game...

- 34Unrestricted-n-in-a-row maker-breaker game is a breakers win for every n>= 40 proof.

- 35Maker and connectivity game theorem.

- 36Maker wins connectivity game on multigraph G then G has two edge-disjoint spanning trees proof.

- 37Lehman theorem.

- 38Lehman if multigraph G has two edge-disjoint spanning tress then maker wins the connectivity game on G proof.

- 39Poset definition.

- 40Poset maximal element definition.

- 41Chain and antichain definition.

- 42Mirsky theorem.

- 43Mirsky theorem: largest chain in P has size r, then P can be partitioned into r antichains, proof.

- 44Dilworth theorem.

- 45Hall theorem.

- 46Hall: a bipartite graph with vertex classes A and B such that |N(S)|>=|S| for all S in A, contains a matching covering all of A, proof,

- 47Sperner’s lemma.

- 48YBLM inequality.

- 49YBLM inequality, proof.

- 50Sperner’s lemma proof.

- 51Erdos theorem.

- 52Erdos theorem proof.

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- Flashcards on Combinatorics, created by Amelia Giles on 12/05/2023.
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- Amelia Giles
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