{"id":3071,"date":"2025-06-06T09:43:30","date_gmt":"2025-06-06T09:43:30","guid":{"rendered":"https:\/\/diznr.com\/?p=3071"},"modified":"2025-06-06T09:43:30","modified_gmt":"2025-06-06T09:43:30","slug":"previous-year-question-papers-gate-gate-1995-relation-let-r-be-a-symmetric-and-relation-transitive","status":"publish","type":"post","link":"https:\/\/www.reilsolar.com\/pdf\/previous-year-question-papers-gate-gate-1995-relation-let-r-be-a-symmetric-and-relation-transitive\/","title":{"rendered":"previous year question papers gate- GATE 1995-relation-Let R be a symmetric and transitive relation."},"content":{"rendered":"<p>previous year question papers gate- GATE 1995-relation-Let R be a symmetric and transitive relation.<\/p>\n<p>[fvplayer id=&#8221;238&#8243;]<\/p>\n<h3 data-start=\"0\" data-end=\"53\"><strong data-start=\"4\" data-end=\"51\">GATE 1995 \u2013 Set Theory &amp; Relations Question<\/strong><\/h3>\n<p data-start=\"54\" data-end=\"195\"><strong data-start=\"57\" data-end=\"70\">Question:<\/strong><br data-start=\"70\" data-end=\"73\" \/>Let <strong data-start=\"77\" data-end=\"82\">R<\/strong> be a <strong data-start=\"88\" data-end=\"101\">symmetric<\/strong> and <strong data-start=\"106\" data-end=\"120\">transitive<\/strong> relation on a set <strong data-start=\"139\" data-end=\"144\">A<\/strong>. Then which of the following is <strong data-start=\"177\" data-end=\"192\">always true<\/strong>?<\/p>\n<p data-start=\"197\" data-end=\"324\">(A) <strong data-start=\"201\" data-end=\"219\">R is reflexive<\/strong><br data-start=\"219\" data-end=\"222\" \/>(B) <strong data-start=\"226\" data-end=\"258\">R is an equivalence relation<\/strong><br data-start=\"258\" data-end=\"261\" \/>(C) <strong data-start=\"265\" data-end=\"288\">R is anti-symmetric<\/strong><br data-start=\"288\" data-end=\"291\" \/>(D) <strong data-start=\"295\" data-end=\"322\">R is reflexive or empty<\/strong><\/p>\n<h3 data-start=\"331\" data-end=\"365\"><strong data-start=\"335\" data-end=\"363\">\u00a0Step-by-Step Solution<\/strong><\/h3>\n<p data-start=\"367\" data-end=\"452\">We are given that <strong data-start=\"385\" data-end=\"418\">R is symmetric and transitive<\/strong>. Let&#8217;s analyze the given options:<\/p>\n<h3 data-start=\"454\" data-end=\"487\"><strong data-start=\"458\" data-end=\"485\">\u00a01. Reflexivity Check<\/strong><\/h3>\n<ul data-start=\"488\" data-end=\"854\">\n<li data-start=\"488\" data-end=\"558\">A relation <strong data-start=\"501\" data-end=\"506\">R<\/strong> is reflexive if <strong data-start=\"523\" data-end=\"537\">(a, a) \u2208 R<\/strong> for all <strong data-start=\"546\" data-end=\"555\">a \u2208 A<\/strong>.<\/li>\n<li data-start=\"559\" data-end=\"674\"><strong data-start=\"561\" data-end=\"599\">R is only symmetric and transitive<\/strong>, but there is no guarantee that it contains <strong data-start=\"644\" data-end=\"654\">(a, a)<\/strong> for all elements.<\/li>\n<li data-start=\"675\" data-end=\"854\"><strong data-start=\"677\" data-end=\"696\">Counterexample:<\/strong> If <strong data-start=\"700\" data-end=\"721\">R = \u2205 (empty set)<\/strong>, it is still symmetric and transitive but <strong data-start=\"764\" data-end=\"781\">not reflexive<\/strong>.<br data-start=\"782\" data-end=\"785\" \/>\u00a0So, <strong data-start=\"791\" data-end=\"825\">R is NOT necessarily reflexive<\/strong> \u2192 <strong data-start=\"828\" data-end=\"852\">(Option A is False).<\/strong><\/li>\n<\/ul>\n<h3 data-start=\"861\" data-end=\"903\"><strong data-start=\"865\" data-end=\"901\">\u00a02. Equivalence Relation Check<\/strong><\/h3>\n<ul data-start=\"904\" data-end=\"1157\">\n<li data-start=\"904\" data-end=\"1000\">A relation is an <strong data-start=\"923\" data-end=\"947\">equivalence relation<\/strong> if it is <strong data-start=\"957\" data-end=\"997\">reflexive, symmetric, and transitive<\/strong>.<\/li>\n<li data-start=\"1001\" data-end=\"1157\">Since <strong data-start=\"1009\" data-end=\"1081\">R is given as symmetric and transitive but NOT necessarily reflexive<\/strong>, it is <strong data-start=\"1089\" data-end=\"1127\">not always an equivalence relation<\/strong>.<br data-start=\"1128\" data-end=\"1131\" \/><strong data-start=\"1133\" data-end=\"1155\">Option B is False.<\/strong><\/li>\n<\/ul>\n<h3 data-start=\"1164\" data-end=\"1199\"><strong data-start=\"1168\" data-end=\"1197\">\u00a03. Anti-Symmetry Check<\/strong><\/h3>\n<ul data-start=\"1200\" data-end=\"1472\">\n<li data-start=\"1200\" data-end=\"1298\">A relation <strong data-start=\"1213\" data-end=\"1218\">R<\/strong> is <strong data-start=\"1222\" data-end=\"1240\">anti-symmetric<\/strong> if <strong data-start=\"1244\" data-end=\"1258\">(a, b) \u2208 R<\/strong> and <strong data-start=\"1263\" data-end=\"1277\">(b, a) \u2208 R<\/strong> implies <strong data-start=\"1286\" data-end=\"1295\">a = b<\/strong>.<\/li>\n<li data-start=\"1299\" data-end=\"1472\">However, since <strong data-start=\"1316\" data-end=\"1334\">R is symmetric<\/strong>, we have <strong data-start=\"1344\" data-end=\"1371\">(a, b) \u2208 R \u21d2 (b, a) \u2208 R<\/strong>, which contradicts anti-symmetry unless <strong data-start=\"1412\" data-end=\"1442\">R is the identity relation<\/strong>.<br data-start=\"1443\" data-end=\"1446\" \/><strong data-start=\"1448\" data-end=\"1470\">Option C is False.<\/strong><\/li>\n<\/ul>\n<h3 data-start=\"1479\" data-end=\"1519\"><strong data-start=\"1483\" data-end=\"1517\">\u00a04. Reflexive or Empty Check<\/strong><\/h3>\n<ul data-start=\"1520\" data-end=\"1769\">\n<li data-start=\"1520\" data-end=\"1769\">If <strong data-start=\"1525\" data-end=\"1530\">R<\/strong> is symmetric and transitive, the only possible cases are:<br data-start=\"1588\" data-end=\"1591\" \/><strong data-start=\"1597\" data-end=\"1615\">R is reflexive<\/strong> (if it contains all (a, a) pairs).<br data-start=\"1650\" data-end=\"1653\" \/><strong data-start=\"1659\" data-end=\"1673\">R is empty<\/strong> (which still satisfies symmetry and transitivity).<br data-start=\"1724\" data-end=\"1727\" \/><strong data-start=\"1729\" data-end=\"1749\">Option D is True<\/strong> (Correct Answer).<\/li>\n<\/ul>\n<h3 data-start=\"1776\" data-end=\"1802\"><strong data-start=\"1780\" data-end=\"1800\">\u00a0Final Answer:<\/strong><\/h3>\n<p data-start=\"1803\" data-end=\"1847\"><strong data-start=\"1805\" data-end=\"1843\">Option (D) R is reflexive or empty<\/strong><\/p>\n<p data-start=\"1849\" data-end=\"1982\" data-is-last-node=\"\" data-is-only-node=\"\">This is a <strong data-start=\"1859\" data-end=\"1883\">common GATE question<\/strong> based on <strong data-start=\"1893\" data-end=\"1920\">properties of relations<\/strong>. Would you like <strong data-start=\"1937\" data-end=\"1964\">more practice questions<\/strong> on this topic?<\/p>\n<h3 data-start=\"1849\" data-end=\"1982\"><a href=\"https:\/\/gateforum.com\/wp-content\/uploads\/2013\/01\/CS-1995.pdf\" target=\"_blank\" rel=\"noopener\">previous year question papers gate- GATE 1995-relation-Let R be a symmetric and transitive relation.<\/a><\/h3>\n<h3 class=\"LC20lb MBeuO DKV0Md\"><a href=\"https:\/\/gateforum.com\/wp-content\/uploads\/2013\/01\/CS-2002.pdf\" target=\"_blank\" rel=\"noopener\">GATE CS &#8211; 1995<\/a><\/h3>\n<p>Here&#8217;s a detailed explanation of the <strong>GATE 1995 question<\/strong> based on <strong>Relations<\/strong> \u2014 specifically focusing on <strong>Symmetric<\/strong> and <strong>Transitive<\/strong> relations.<\/p>\n<hr \/>\n<h2>\ud83e\udde0 <strong>GATE 1995 \u2013 Set Theory \/ Relations Question<\/strong><\/h2>\n<h3>\u2753<strong>Question:<\/strong><\/h3>\n<p>Let <span class=\"katex\">RR<\/span> be a <strong>symmetric<\/strong> and <strong>transitive<\/strong> relation on a set <span class=\"katex\">AA<\/span>. Suppose <span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span>.<br \/>\nThen which of the following must also be true?<\/p>\n<p><strong>Options (typical structure):<\/strong><br \/>\nA) <span class=\"katex\">(b,a)\u2208R(b, a) \\in R<\/span><br \/>\nB) <span class=\"katex\">(a,a)\u2208R(a, a) \\in R<\/span><br \/>\nC) <span class=\"katex\">(b,b)\u2208R(b, b) \\in R<\/span><br \/>\nD) All of the above<\/p>\n<hr \/>\n<h2>\u2705 <strong>Solution with Concept:<\/strong><\/h2>\n<p>We are given:<\/p>\n<ul>\n<li><span class=\"katex\">RR<\/span> is <strong>symmetric<\/strong>:<br \/>\nIf <span class=\"katex\">(a,b)\u2208R\u21d2(b,a)\u2208R(a, b) \\in R \\Rightarrow (b, a) \\in R<\/span><\/li>\n<li><span class=\"katex\">RR<\/span> is <strong>transitive<\/strong>:<br \/>\nIf <span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span> and <span class=\"katex\">(b,c)\u2208R\u21d2(a,c)\u2208R(b, c) \\in R \\Rightarrow (a, c) \\in R<\/span><\/li>\n<\/ul>\n<p>And we are told:<br \/>\n<span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span><\/p>\n<hr \/>\n<h3>\ud83d\udd0d Step-by-step Reasoning:<\/h3>\n<ol>\n<li><strong>From symmetry<\/strong>:<br \/>\nSince <span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span>, \u21d2 <span class=\"katex\">(b,a)\u2208R(b, a) \\in R<\/span><\/li>\n<li><strong>Now apply transitivity<\/strong>:\n<ul>\n<li>From <span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span> and <span class=\"katex\">(b,a)\u2208R(b, a) \\in R<\/span><br \/>\n\u21d2 By transitivity: <span class=\"katex\">(a,a)\u2208R(a, a) \\in R<\/span> \u2705<\/li>\n<\/ul>\n<\/li>\n<li>Also:\n<ul>\n<li>From <span class=\"katex\">(b,a)\u2208R(b, a) \\in R<\/span> and <span class=\"katex\">(a,b)\u2208R(a, b) \\in R<\/span><br \/>\n\u21d2 <span class=\"katex\">(b,b)\u2208R(b, b) \\in R<\/span> \u2705<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<hr \/>\n<h3>\u2705 Final Answer:<\/h3>\n<p><strong>D) All of the above<\/strong><\/p>\n<hr \/>\n<h3>\ud83d\udccc GATE Concept Summary:<\/h3>\n<table>\n<thead>\n<tr>\n<th><strong>Property<\/strong><\/th>\n<th><strong>Definition<\/strong><\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>Symmetric<\/strong><\/td>\n<td><span class=\"katex\">(a,b)\u2208R\u21d2(b,a)\u2208R(a, b) \\in R \\Rightarrow (b, a) \\in R<\/span><\/td>\n<\/tr>\n<tr>\n<td><strong>Transitive<\/strong><\/td>\n<td><span class=\"katex\">(a,b),(b,c)\u2208R\u21d2(a,c)\u2208R(a, b), (b, c) \\in R \\Rightarrow (a, c) \\in R<\/span><\/td>\n<\/tr>\n<tr>\n<td><strong>Reflexive<\/strong><\/td>\n<td><span class=\"katex\">(a,a)\u2208R\u2200a\u2208A(a, a) \\in R \\forall a \\in A<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong>Note:<\/strong><br \/>\nEven though reflexivity is not given, due to symmetry + transitivity and the presence of <span class=\"katex\">(a,b)(a, b)<\/span>, we were able to deduce <span class=\"katex\">(a,a)(a, a)<\/span> and <span class=\"katex\">(b,b)(b, b)<\/span> as members of <span class=\"katex\">RR<\/span>.<\/p>\n<hr \/>\n<p>Would you like a PDF of:<\/p>\n<ul>\n<li>\u2705 All GATE relation-based questions (1991\u20132024)?<\/li>\n<li>\u2705 Concept revision sheet (Properties of Relations)?<\/li>\n<li>\u2705 Practice questions with Venn diagrams?<\/li>\n<\/ul>\n<p>Let me know and I\u2019ll prepare it for you!<\/p>\n<h3><a href=\"https:\/\/www.math.fsu.edu\/~pkirby\/mad3105\/GeneralDocs\/sp06PracTests\/t1pracsol.pdf\" target=\"_blank\" rel=\"noopener\">previous year question papers gate- GATE 1995-relation-Let R be a symmetric and transitive relation.<\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"<p>previous year question papers gate- GATE 1995-relation-Let R be a symmetric and transitive relation. [fvplayer id=&#8221;238&#8243;] GATE 1995 \u2013 Set Theory &amp; Relations Question Question:Let R be a symmetric and transitive relation on a set A. Then which of the following is always true? (A) R is reflexive(B) R is an equivalence relation(C) R is [&hellip;]<\/p>\n","protected":false},"author":71,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[76],"tags":[],"class_list":["post-3071","post","type-post","status-publish","format-standard","hentry","category-discrete-mathematics"],"_links":{"self":[{"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/posts\/3071","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/users\/71"}],"replies":[{"embeddable":true,"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/comments?post=3071"}],"version-history":[{"count":0,"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/posts\/3071\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/media?parent=3071"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/categories?post=3071"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.reilsolar.com\/pdf\/wp-json\/wp\/v2\/tags?post=3071"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}