. }$, $= (n-1)! Mathematics of Master Discrete Mathematics for Computer Science with Graph Theory and Logic (Discrete Math)" today and start learning. There are 6 men and 5 women in a room. There are $50/3 = 16$ numbers which are multiples of 3. The Basic Counting Principle. Very Important topics: Propositional and first-order logic, Groups, Counting, Relations, introduction to graphs, connectivity, trees / [(a_1!(a_2!) In combinatorics, double counting, also called counting in two ways, is a combinatorial proof technique for showing that two expressions are equal by demonstrating that they are two ways of counting the size of one set. For solving these problems, mathematical theory of counting are used. /Length 1123 Discrete Mathematics is a branch of mathematics involving discrete elements that uses algebra and arithmetic. Number of permutations of n distinct elements taking n elements at a time = $n_{P_n} = n!$, The number of permutations of n dissimilar elements taking r elements at a time, when x particular things always occupy definite places = $n-x_{p_{r-x}}$, The number of permutations of n dissimilar elements when r specified things always come together is − $r! The cardinality of the set is 6 and we have to choose 3 elements from the set. So, $|A|=25$, $|B|=16$ and $|A \cap B|= 8$. = 180.$. There are n number of ways to fill up the first place. Active 10 years, 6 months ago. Probability. So, Enroll in this "Mathematics:Discrete Mathematics for Computer Science . Example: There are 6 flavors of ice-cream, and 3 different cones. Group theory. Graph theory. Mathematically, for any positive integers k and n: $^nC_{k} = ^n{^-}^1C_{k-1} + ^n{^-}^1{C_k}$, $= \frac{ (n-1)! } %PDF-1.5 Discrete Mathematics & Mathematical Reasoning Chapter 6: Counting Colin Stirling Informatics Slides originally by Kousha Etessami Colin Stirling (Informatics) Discrete Mathematics (Chapter 6) Today 1 / 39. What is Discrete Mathematics Counting Theory? Discrete Mathematics (c)Marcin Sydow Productand SumRule Inclusion-Exclusion Principle Pigeonhole Principle Permutations Generalised Permutations andCombi-nations Combinatorial Proof Binomial Coefficients DiscreteMathematics Counting (c)MarcinSydow Would this be 10! For two sets A and B, the principle states −, $|A \cup B| = |A| + |B| - |A \cap B|$, For three sets A, B and C, the principle states −, $|A \cup B \cup C | = |A| + |B| + |C| - |A \cap B| - |A \cap C| - |B \cap C| + |A \cap B \cap C |$, $|\bigcup_{i=1}^{n}A_i|=\sum\limits_{1\leq i�Ytw�8FqX��χU�]A�|D�C#}��kW��v��G �������m����偅^~�l6��&) ��J�1��v}�â�t�Wr���k��U�k��?�d���B�n��c!�^Հ�T�Ͳm�х�V��������6�q�o���Юn�n?����˳���x�q@ֻ[ ��XB&`��,f|����+��M`#R������ϕc*HĐ}�5S0H $A \cap B = \emptyset$), then mathematically $|A \cup B| = |A| + |B|$, The Rule of Product − If a sequence of tasks $T_1, T_2, \dots, T_m$ can be done in $w_1, w_2, \dots w_m$ ways respectively and every task arrives after the occurrence of the previous task, then there are $w_1 \times w_2 \times \dots \times w_m$ ways to perform the tasks. . . . Thank you. How many ways are there to go from X to Z? . 70 0 obj << From there, he can either choose 4 bus routes or 5 train routes to reach Z. That means 3×4=12 different outfits. . of ways to fill up from first place up to r-th-place −, $n_{ P_{ r } } = n (n-1) (n-2)..... (n-r + 1)$, $= [n(n-1)(n-2) ... (n-r + 1)] [(n-r)(n-r-1) \dots 3.2.1] / [(n-r)(n-r-1) \dots 3.2.1]$. $|A \cup B| = |A| + |B| - |A \cap B| = 25 + 16 - 8 = 33$. From a set S ={x, y, z} by taking two at a time, all permutations are −, We have to form a permutation of three digit numbers from a set of numbers $S = \lbrace 1, 2, 3 \rbrace$. . Sign up for free to create engaging, inspiring, and converting videos with Powtoon. Set theory is a very important topic in discrete mathematics . Counting mainly encompasses fundamental counting rule, the permutation rule, and the combination rule. }$$. Problem 2 − In how many ways can the letters of the word 'READER' be arranged? . There are $50/6 = 8$ numbers which are multiples of both 2 and 3. . Topics covered includes: Mathematical logic, Set theory, The real numbers, Induction and recursion, Summation notation, Asymptotic notation, Number theory, Relations, Graphs, Counting, Linear algebra, Finite fields. If we consider two tasks A and B which are disjoint (i.e. . Number of ways of arranging the consonants among themselves $= ^3P_{3} = 3! . . Some of the discrete math topic that you should know for data science sets, power sets, subsets, counting functions, combinatorics, countability, basic proof techniques, induction, ... Information theory is also widely used in math for data science. For choosing 3 students for 1st group, the number of ways − $^9C_{3}$, The number of ways for choosing 3 students for 2nd group after choosing 1st group − $^6C_{3}$, The number of ways for choosing 3 students for 3rd group after choosing 1st and 2nd group − $^3C_{3}$, Hence, the total number of ways $= ^9C_{3} \times ^6C_{3} \times ^3C_{3} = 84 \times 20 \times 1 = 1680$. material, may be used as a textbook for a formal course in discrete mathematics or as a supplement to all current texts. Hence, there are (n-1) ways to fill up the second place. It is increasingly being applied in the practical fields of mathematics and computer science. In this technique, which van Lint & Wilson (2001) call “one of the most important tools in combinatorics,” one describes a finite set X from two perspectives leading to two distinct expressions … Then, number of permutations of these n objects is = $n! Starting from the 6th grade, students should some effort into studying fundamental discrete math, especially combinatorics, graph theory, discrete geometry, number theory, and discrete probability. Discrete mathematics problem - Probability theory and counting [closed] Ask Question Asked 10 years, 6 months ago. This is a course note on discrete mathematics as used in Computer Science. Welcome to Discrete Mathematics 2, a course introducting Inclusion-Exclusion, Probability, Generating Functions, Recurrence Relations, and Graph Theory. in the word 'READER'. Make an Impact. Below, you will find the videos of each topic presented. . Problem 1 − From a bunch of 6 different cards, how many ways we can permute it? Proof − Let there be ‘n’ different elements. + \frac{ (n-1)! } For solving these problems, mathematical theory of counting are used. . The remaining 3 vacant places will be filled up by 3 vowels in $^3P_{3} = 3! Viewed 4k times 2. . . . . After filling the first and second place, (n-2) number of elements is left. %���� . I'm taking a discrete mathematics course, and I encountered a question and I need your help. . A combination is selection of some given elements in which order does not matter. ����M>�,oX��`�N8xT����,�0�z�I�Q������������[�I9r0� '&l�v]G�q������i&��b�i� �� �`q���K�?�c�Rl If each person shakes hands at least once and no man shakes the same man’s hand more than once then two men took part in the same number of handshakes. The Inclusion-exclusion principle computes the cardinal number of the union of multiple non-disjoint sets. Discrete Mathematics Course Notes by Drew Armstrong. 2 CS 441 Discrete mathematics for CS M. Hauskrecht Basic counting rules • Counting problems may be hard, and easy solutions are not obvious • Approach: – simplify the solution by decomposing the problem • Two basic decomposition rules: – Product rule • A count decomposes into a sequence of dependent counts There must be at least two people in a class of 30 whose names start with the same alphabet. He may go X to Y by either 3 bus routes or 2 train routes. Boolean Algebra. From his home X he has to first reach Y and then Y to Z. We can now generalize the number of ways to fill up r-th place as [n – (r–1)] = n–r+1, So, the total no. Let X be the set of students who like cold drinks and Y be the set of people who like hot drinks. How many integers from 1 to 50 are multiples of 2 or 3 but not both? .10 2.1.3 Whatcangowrong. Hence, the total number of permutation is $6 \times 6 = 36$. The Rule of Sum and Rule of Product are used to decompose difficult counting problems into simple problems. \dots (a_r!)]$. Solution − There are 3 vowels and 3 consonants in the word 'ORANGE'. The applications of set theory today in computer science is countless. Question − A boy lives at X and wants to go to School at Z. . . . (1!)(1!)(2!)] So, $| X \cup Y | = 50$, $|X| = 24$, $|Y| = 36$, $|X \cap Y| = |X| + |Y| - |X \cup Y| = 24 + 36 - 50 = 60 - 50 = 10$. When there are m ways to do one thing, and n ways to do another, then there are m×n ways of doing both. Discrete Mathematics Handwritten Notes PDF. It is a very good tool for improving reasoning and problem-solving capabilities. + \frac{ n-k } { k!(n-k)! } If there are n elements of which $a_1$ are alike of some kind, $a_2$ are alike of another kind; $a_3$ are alike of third kind and so on and $a_r$ are of $r^{th}$ kind, where $(a_1 + a_2 + ... a_r) = n$. . 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