<?xml version="1.0" encoding="UTF-8"?><rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:atom="http://www.w3.org/2005/Atom" version="2.0"><channel><title><![CDATA[RSS Feed]]></title><description><![CDATA[RSS Feed]]></description><link>http://direct.ecency.com</link><image><url>http://direct.ecency.com/logo512.png</url><title>RSS Feed</title><link>http://direct.ecency.com</link></image><generator>RSS for Node</generator><lastBuildDate>Mon, 13 Apr 2026 11:26:57 GMT</lastBuildDate><atom:link href="http://direct.ecency.com/created/combinatorics/rss.xml" rel="self" type="application/rss+xml"/><item><title><![CDATA[Stars & Bars Method For Counting Problems [Math]]]></title><description><![CDATA[Hi there. In this math post I cover this Stars & Bars Method for counting and arrangement problems. This is something I came across while helping out a student. My permutations & combinations knowledge]]></description><link>http://direct.ecency.com/hive-163521/@dkmathstats/stars-and-bars-method-for-counting-problems-math</link><guid isPermaLink="true">http://direct.ecency.com/hive-163521/@dkmathstats/stars-and-bars-method-for-counting-problems-math</guid><category><![CDATA[hive-163521]]></category><dc:creator><![CDATA[dkmathstats]]></dc:creator><pubDate>Tue, 05 Nov 2024 16:40:15 GMT</pubDate><enclosure url="https://images.ecency.com/p/FxX5caie56ynMuadCn1QV74TFBJ4dhAkvfmnAiCuCBqjmjgACbR8S7d5BZFdACmDWu8BQCfncQdKQLK58Up4vCr6Zp4uaJ4jFjhmQ4kb3Z6v?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Suma  de  subconjuntos. Subset  sum.⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀]]></title><description><![CDATA[EspañolEnglish Dado un conjunto arbitrario de enteros,¿Existe un subconjunto cuya suma sea exactamente un valor dado?               ]]></description><link>http://direct.ecency.com/hive-163521/@j2e2xae/suma-de-subconjuntos-subset-sum</link><guid isPermaLink="true">http://direct.ecency.com/hive-163521/@j2e2xae/suma-de-subconjuntos-subset-sum</guid><category><![CDATA[hive-163521]]></category><dc:creator><![CDATA[j2e2xae]]></dc:creator><pubDate>Fri, 12 Jul 2024 18:15:27 GMT</pubDate><enclosure url="https://images.ecency.com/p/tdyZKgpV6mxDTPCVRJtFoDzToiM3aBB58VES399fLHxagY4v2kpTe16gFSkXEYM8Bg3MCsJFXWXGARX4r8x8znPmHwNWgc8CfZXBreMkPyDxksCXsU7fnFmvVLZnjpfzJ9mgnLVxNwF94pDcacSRcSCAewTxZcYaQXgYwaCQWFgKFTQcWNcuFcU2RNAUkyF?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Mathematics - Discrete Mathematics - Combinatorics Topics]]></title><description><![CDATA[[Image 1] Introduction Hey it's a me again @drifter1! Today we continue with Mathematics, and more specifically the branch of "Discrete Mathematics", in order to get into Combinatorics Topics.]]></description><link>http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinatorics-topics</link><guid isPermaLink="true">http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinatorics-topics</guid><category><![CDATA[hive-163521]]></category><dc:creator><![CDATA[drifter1]]></dc:creator><pubDate>Sun, 20 Mar 2022 10:39:09 GMT</pubDate><enclosure url="https://images.ecency.com/p/46aP2QbqUqBrRwi79dxv9NTieZ7DBL8E8ktFVBQ3ZiFxoYVwKWK6CHCtumQADwFBP1CQjVU8rokm6PoD1DT4zyATt7bc?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Mathematics - Discrete Mathematics - Combinations and Permutations]]></title><description><![CDATA[[Image 1] Introduction Hey it's a me again @drifter1! Today we continue with Mathematics, and more specifically the branch of "Discrete Mathematics", in order to get into Combinations and]]></description><link>http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinations-and-permutations</link><guid isPermaLink="true">http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinations-and-permutations</guid><category><![CDATA[hive-163521]]></category><dc:creator><![CDATA[drifter1]]></dc:creator><pubDate>Sat, 19 Mar 2022 10:34:09 GMT</pubDate><enclosure url="https://images.ecency.com/p/46aP2QbqUqBrRwi79dxv9NTieZ7DBL8E8ktFVBQ3ZiFxoYVwKWK6CHCtumQADwFBP1CQjVU8rokm6PoD1DT4zyATt7bc?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Mathematics - Discrete Mathematics - Combinatorial Principles]]></title><description><![CDATA[[Image 1] Introduction Hey it's a me again @drifter1! Today we continue with Mathematics, and more specifically the branch of "Discrete Mathematics", in order to get into Combinatorial Principles.]]></description><link>http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinatorial-principles</link><guid isPermaLink="true">http://direct.ecency.com/hive-163521/@drifter1/mathematics-discrete-mathematics-combinatorial-principles</guid><category><![CDATA[hive-163521]]></category><dc:creator><![CDATA[drifter1]]></dc:creator><pubDate>Fri, 18 Mar 2022 12:21:03 GMT</pubDate><enclosure url="https://images.ecency.com/p/46aP2QbqUqBrRwi79dxv9NTieZ7DBL8E8ktFVBQ3ZiFxoYVwKWK6CHCtumQADwFBP1CQjVU8rokm6PoD1DT4zyATt7bc?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Math mini-contest problem on D.Buzz for July 2021 [Day 1 - Problem B] 😎]]></title><description><![CDATA[Math mini-contest problem on D.Buzz for July 2021 [Day 1, Problem B] 😎 A player has 8 cards numbered 1, 2, 3, 4, 4, 5, 6, and 8, respectively. How many ways can that player create a set of 1 to 6 cards]]></description><link>http://direct.ecency.com/hive-193084/@savvyplayer/julymathday1b</link><guid isPermaLink="true">http://direct.ecency.com/hive-193084/@savvyplayer/julymathday1b</guid><category><![CDATA[hive-193084]]></category><dc:creator><![CDATA[savvyplayer]]></dc:creator><pubDate>Wed, 28 Jul 2021 19:08:57 GMT</pubDate></item><item><title><![CDATA[Partitioning a set into lists]]></title><description><![CDATA[The Bell numbers count how many ways there are to partition N elements into sets. What if we want to partition the elements into ordered groups instead, as this Quora question asks? For example, {a,b}]]></description><link>http://direct.ecency.com/steemstem/@markgritter/partitioning-a-set-into-lists</link><guid isPermaLink="true">http://direct.ecency.com/steemstem/@markgritter/partitioning-a-set-into-lists</guid><category><![CDATA[steemstem]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Sun, 20 Jan 2019 05:32:21 GMT</pubDate></item><item><title><![CDATA[the Dehn–Sommerville equations]]></title><description><![CDATA[Thanks to a video I saw on Youtube, I know now a way to prove both the relations I used in this post. First a few notations: Given a closed simply connected (without holes) domain on the plane, let B >]]></description><link>http://direct.ecency.com/mathematics/@zipity/the-dehn-sommerville-equations</link><guid isPermaLink="true">http://direct.ecency.com/mathematics/@zipity/the-dehn-sommerville-equations</guid><category><![CDATA[mathematics]]></category><dc:creator><![CDATA[zipity]]></dc:creator><pubDate>Tue, 04 Dec 2018 16:00:00 GMT</pubDate><enclosure url="https://images.ecency.com/p/qjrE4yyfw5pEPvDbJDzhdNXM7mjt1tbr2kM3X28F6SraZgEKzwtgbELn2jBKMPxvxwSauz4JzNCZbEsb7qWHGazka7ZfHWaqCpsa5K1nWvGWMKnFgNUDLPE6?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Counting the Number of 2-State 2-Dimensional Symmetric Cellular Automata]]></title><description><![CDATA[Suppose we have a two-state cellular automaton using the Moore neighborhood, which counts both orthogonal and diagonal neighbors. How many possible rules are there? With 9 cells total (including the center]]></description><link>http://direct.ecency.com/steemstem/@markgritter/counting-the-number-of-2-state-2-dimensional-symmetric-cellular-automata</link><guid isPermaLink="true">http://direct.ecency.com/steemstem/@markgritter/counting-the-number-of-2-state-2-dimensional-symmetric-cellular-automata</guid><category><![CDATA[steemstem]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Sat, 01 Dec 2018 19:32:42 GMT</pubDate><enclosure url="https://images.ecency.com/p/C3TZR1g81UNaPs7vzNXHueW5ZM76DSHWEY7onmfLxcK2iQHZQJnXyihcHarqLGMZewiziZYqEHCdEWwVHkQ81iTGsrAqa83PeRfdNdQ68rdVGx64nP3Drqc?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Plotting all integer lattice paths from (0,0) to (3,5)]]></title><description><![CDATA[If you start at (0,0) and can take one step at a time either north (0,+1) or east (+1,0), how many different ways are there to get to (3,5)? I wanted to augment this answer on Quora with a visual]]></description><link>http://direct.ecency.com/python/@markgritter/plotting-all-integer-lattice-paths-from-0-0-to-3-5</link><guid isPermaLink="true">http://direct.ecency.com/python/@markgritter/plotting-all-integer-lattice-paths-from-0-0-to-3-5</guid><category><![CDATA[python]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Mon, 26 Nov 2018 05:45:15 GMT</pubDate><enclosure url="https://images.ecency.com/p/2r8F9rTBenJQfQgENfxADE6EVYabczqmSF5KeWefV5WL9WBNNKeLfmYW5eLBJszsvhkSwRG4f4fD2e39VhLYUSJMhY1MRUdNARFuM1cn6UeGz94xqDepPEjYKtFyKGGHt?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[How many 3-clubs can a graph have?]]></title><description><![CDATA[A K-club on a graph is a subset of the vertices such that the diameter of the induced subgraph is less than or equal to K. "Induced subgraph" just means "pick all the edges which both endpoints]]></description><link>http://direct.ecency.com/mathematics/@markgritter/how-many-3-clubs-can-a-graph-have</link><guid isPermaLink="true">http://direct.ecency.com/mathematics/@markgritter/how-many-3-clubs-can-a-graph-have</guid><category><![CDATA[mathematics]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Sun, 25 Nov 2018 06:54:57 GMT</pubDate><enclosure url="https://images.ecency.com/p/C3TZR1g81UNaPs7vzNXHueW5ZM76DSHWEY7onmfLxcK2iQWqUEj59AMNQXyprTaDmmhqmKgJMyTrxuhVrzpowascdCTy1rGyhwR5EEmi2QbiCDqXx7MD3Lr?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[How many "incomplete open hypercubes" are there in four dimensions?]]></title><description><![CDATA[Sol LeWitt's artwork "Incomplete Open Cubes" enumerates all distinct connected sets of edges of the cube which do not collapse into a smaller dimension (a figure that lies in the plane, or a]]></description><link>http://direct.ecency.com/stemq/@markgritter/how-many-incomplete-open-hypercubes-are-there-in-four-dimensions</link><guid isPermaLink="true">http://direct.ecency.com/stemq/@markgritter/how-many-incomplete-open-hypercubes-are-there-in-four-dimensions</guid><category><![CDATA[stemq]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Fri, 02 Nov 2018 16:45:03 GMT</pubDate><enclosure url="https://images.ecency.com/p/3jpR3paJ37V8JxyWvtbhvcm5k3roJwHBR4WTALx7XaoRovbggwB82cDnZ7Pus1fthai13L8U2GV53picxMppP9A9i1VJtKiJK3drDYihXFPWdUgQEn6w5pr5oy3eRKtWBRZMY?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Discard Trees: a data structure for finding nonintersecting combinations]]></title><description><![CDATA[A "discard tree" is a data structure I invented that is keyed by bitvectors representing K-combinations. It permits us to efficiently find all bitvectors that do not intersect with the search]]></description><link>http://direct.ecency.com/programming/@markgritter/discard-trees-a-data-structure-for-finding-nonintersecting-combinations</link><guid isPermaLink="true">http://direct.ecency.com/programming/@markgritter/discard-trees-a-data-structure-for-finding-nonintersecting-combinations</guid><category><![CDATA[programming]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Sun, 16 Sep 2018 23:01:03 GMT</pubDate><enclosure url="https://images.ecency.com/p/C3TZR1g81UNaPs7vzNXHueW5ZM76DSHWEY7onmfLxcK2iPJP659gJ8X2akSZeRd5ehUzr3uvAn3JEcWd7ZYbxoK2McE4d6eqU74QvdUfyn4QCqaL6ZdHbYS?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Minimal covering combination sets]]></title><description><![CDATA[In abstract terms: Given an N-element set, how many L-element subsets do we need so that every K-element subset is a superset of one of the L-element subsets? Let's express this by saying that the family]]></description><link>http://direct.ecency.com/mathematics/@markgritter/minimal-covering-combination-sets</link><guid isPermaLink="true">http://direct.ecency.com/mathematics/@markgritter/minimal-covering-combination-sets</guid><category><![CDATA[mathematics]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Fri, 14 Sep 2018 06:07:03 GMT</pubDate><enclosure url="https://images.ecency.com/p/C3TZR1g81UNaPs7vzNXHueW5ZM76DSHWEY7onmfLxcK2iPZMzPmxzSRQz36aPAgBPtzTxjfpFAgtBsMKyTW1eNTbF5KHcDTcsRLLBoEFCzYoJd1UwYJbYdc?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Counting Outs in Lowball]]></title><description><![CDATA[A key feature of lowball games such as Razz or Deuce-to-Seven Triple Draw is that all players are competing to make hands using the same set of low cards. Thus it is fairly common that some of the cards]]></description><link>http://direct.ecency.com/poker/@markgritter/counting-outs-in-lowball</link><guid isPermaLink="true">http://direct.ecency.com/poker/@markgritter/counting-outs-in-lowball</guid><category><![CDATA[poker]]></category><dc:creator><![CDATA[markgritter]]></dc:creator><pubDate>Sun, 03 Jun 2018 20:46:24 GMT</pubDate></item><item><title><![CDATA[Basic Combinatorics, Part Two]]></title><description><![CDATA[Image source: In my previous post, I introduced some basic concepts in combinatorics. If you haven't read the previous post, you can do so here. Arranging objects when some objects are identical A common]]></description><link>http://direct.ecency.com/mathematics/@drdawud/basic-combinatorics-part-two</link><guid isPermaLink="true">http://direct.ecency.com/mathematics/@drdawud/basic-combinatorics-part-two</guid><category><![CDATA[mathematics]]></category><dc:creator><![CDATA[drdawud]]></dc:creator><pubDate>Fri, 16 Mar 2018 21:13:54 GMT</pubDate><enclosure url="https://images.ecency.com/p/2gsjgna1uruvUuS7ndh9YqVwYGPLVszbFLwwpAYXZuRdb5p7nL5ojeNSd7jSsXQZPMbNfTbJciv7CvQHrLC26mbuFtx1vv7cHMUaP2CxXMZhnAmRGJ?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Free Books: M. Lothaire's Books on Combinatorics on Words]]></title><description><![CDATA[Two Books made freely available by "M.Lothaire" (M.Lothaire is a collective name chosen by the authors). It is all about "combinatorics on words" with theory, algorithms applied to]]></description><link>http://direct.ecency.com/science/@boucaron/free-books-m-lothaire-s-books-on-combinatorics-on-words</link><guid isPermaLink="true">http://direct.ecency.com/science/@boucaron/free-books-m-lothaire-s-books-on-combinatorics-on-words</guid><category><![CDATA[science]]></category><dc:creator><![CDATA[boucaron]]></dc:creator><pubDate>Mon, 02 Oct 2017 15:01:45 GMT</pubDate><enclosure url="https://images.ecency.com/p/5CEvyaAfMXebL8zznWk41kFoKZZDytJGAfP2pkfrwbcMdPmPJu7YvqYDjSgfwxHcNk43w84K1GVRj28mk?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Simple Counting Question]]></title><description><![CDATA[How many ways are there to place 20 generic balls into 4 unique bins? This is a simple combinatorics question and I'll post a cool way of thinking about the answer tomorrow...leave any guesses in the comments]]></description><link>http://direct.ecency.com/math/@jackeown/simple-counting-question</link><guid isPermaLink="true">http://direct.ecency.com/math/@jackeown/simple-counting-question</guid><category><![CDATA[math]]></category><dc:creator><![CDATA[jackeown]]></dc:creator><pubDate>Mon, 11 Sep 2017 22:47:30 GMT</pubDate></item><item><title><![CDATA[Today I Am Going To Teach You How To Count… No, You Don’t Know!]]></title><description><![CDATA[Combinatorics ”the branch of mathematics dealing with combinations of objects belonging to a finite set in accordance with certain constraints, such as those of graph theory.” – Google Definition I loved]]></description><link>http://direct.ecency.com/mathematics/@hansenator/today-i-am-going-to-teach-you-how-to-count-no-you-don-t-know</link><guid isPermaLink="true">http://direct.ecency.com/mathematics/@hansenator/today-i-am-going-to-teach-you-how-to-count-no-you-don-t-know</guid><category><![CDATA[mathematics]]></category><dc:creator><![CDATA[hansenator]]></dc:creator><pubDate>Mon, 24 Jul 2017 16:40:54 GMT</pubDate><enclosure url="https://images.ecency.com/p/8SzwQc8j2KJb4ARrxQxCjX4jizub4U5CAK3WwB89p8SiN3S8EikThUvDUQ2RZyCDYSYzJ3CqR42qznao1aEgDxYJxY7zqCedSKPeAKdzxyVZcYLS9ca?format=match&amp;mode=fit" length="0" type="false"/></item><item><title><![CDATA[Hello Steemit!  I'm a math grad student in Miami, Florida.]]></title><description><![CDATA[I heard about steemit from my awesome brother Jack, @jacKeown.  He told me it would be a good community for me to become a part of so I plan to post a lot about the things I'm interested in; namely]]></description><link>http://direct.ecency.com/introduceyourself/@mckeown12/hello-steemit-i-m-a-math-grad-student-in-miami-florida</link><guid isPermaLink="true">http://direct.ecency.com/introduceyourself/@mckeown12/hello-steemit-i-m-a-math-grad-student-in-miami-florida</guid><category><![CDATA[introduceyourself]]></category><dc:creator><![CDATA[mckeown12]]></dc:creator><pubDate>Tue, 20 Jun 2017 22:00:24 GMT</pubDate><enclosure url="https://images.ecency.com/p/4qEixiWLF1XTMPqr8X6VzTtgkrQPJytq6nungPEmaBLXA79GbdiM2aPTpKEv5FZmci?format=match&amp;mode=fit" length="0" type="false"/></item></channel></rss>