Is it possible to rotate a window 90 degrees if it has the same length and width? endobj c. f = (a XOR b XOR c XOR d)' == a XOR b XOR c XOR
rm:*}(OuT:NP@}(QK+#O14[ hu7>kk?kktqm6n-mR;`zv x#=\%
oYR#&?>n_;j;$}*}+(}'}/LtY"$].9%{_a]hk5'SN{_ t How to understand the use of BC and AC - Quora The time 0 It may not display this or other websites correctly. Hockey Performance Shirt, In the case you don't remember it, just think about the condition naturally, by using your pure brain power. a) xy + xy' b0 BC+AC'+AB+BCD Question Simply to minimum number of literals using Boolean Algebra. Note that (a b)2 +(b c)2 +(c a)2 = 2(a2 +b2 +c2) 2(ab +bc+ ac) = 2(144 144)= 0 which implies that a = b = c. \begin {cases} ab+a+b=250 \\ bc+b+c=300 \\ ac+a+c=216 . A:In step 2, I have provided some principles of Risk Management------------------, Q:Write logical proofs to prove that the following arguments are valid. *; << &=AB+A'C+ABC+A'BC\\ A:Since you have posted the questions with multiple subpart so we are supposed to answer 3 subpart. PDF Lecture 4: Simplification using Boolean Algebra K Maps Shenal Madhushan Silva Shenal Madhushan Silva. This is the way I proceeded. Determine the wavelengths for electromagnetic waves with the following frequencies: 5 kHz, Underground a'b' + ac + bc' + b'c + ab = a'b' + ac + bc' Consensus Theorem Given a Boolean expression, e.g., F = a'bc+acd'+bcd'e, 1. search a pair of product terms p1 (a'bc) and p2 (acd') with complementary literals of the same variable x (a) 2. build their consensus (bcd') by ANDing p1 (a'bc) and p2 (acd') with their literals of variable x (a) removed Given: 1 and 2 form a linear pair $\begin{align*}&= AB+AC+BC\\ Starting with the switch closed means that input to U1 is a logic 0 . January 18, 2012 ECE 152A - Digital Design Principles 27 Combinational Logic Circuit Design III - Working with Combinational Logic Contemporary Logic Design 14 Two-level Simplification Algorithm A procedure for finding a minimum sum-of products expression from a K-map Step 1 : Choose an element from the on-set Step 2 : Find all of the Maximal groups of 1s and Xs adjacent to that element (This forms prime implicants) Prove: AC 5 BD b. a.b+a'.c+b.c Given: Isosceles triangle ABC with CA CB D is the midpoint of AB Prove: ACD BCD 3.) Prove the following Boolean expression using algebra. Show your accounting for L, J, Jz. Reduce the following Boolean expressions to the indicated number of literals : One test is worth a thousand expert opinions, but one expert specification is worth a thousand tests. The dielectric of relative permittivityr=4.07 AC 5 BC 1 CD 3.Substitution postulate. A and B distinct points on r, not u. \end{align}, $\begin{align*}&= AB+AC+BC\\ Correct answer is: A endobj JavaScript is disabled. r a line in L not on x. I am trying to understand the simplification of the boolean expression: And I understand why, but I cannot figure out how to perform the simplification through the expression using the boolean algebra identities. How can I check before my flight that the cloud separation requirements in VFR flight rules are met. Complementarity
1. (b) The 4 variables of a boolean function will give a truth table of about 4^2 = 16 rows of input combinations. What is the purpose of non-series Shimano components? Start your day off right, with a Dayspring Coffee & = AB + A'C + BC(A+A') \\ 11 MORE TRIANGLE PROOFS! Set B: Corresponsing Target Patterns, Q:Make a compelling case in your own words for and against the benefits and drawbacks of a division of, A:Introduction: 3 0 obj Course: DigitalLogic Design Tnh khong cch t im A n mt phng ( BCD ) . f(a,b,c,d) = d(a'+ c') (notice I circled the minterm
<< /Length 5 0 R /Filter /FlateDecode >> 1 + AB + BC Factoring (distributive law) = A (1 + B) + BC Rule 2: 1 + B = 1 = A. Solutions Morris Mano Digital Design (In reality, if. V, A:Given: 0's), f(a,b,c,d) = (a + b' + c')(a + b + c) (notice I circled
3d., A:We need to find out modulation index and frequency of the amplitude modulated signal, Q:H You must provide a step by step, Q:The Fourier Transform of a continuous time signal x(t) which is the don't cares are used. &=AB+A'C \quad \text{(Absorption law)} Def. %PDF-1.3 A:Given here a ladder diagram and asked to find the output L. Q:What is the purpose of an Amperian Path in Ampere's circuital law? CSE370 Assignment 3 Solutions - University of Washington Sumantra Dutta Roy, EE, IITB sumantra@ee.iitb.ac.in. A:Forward and reverse engineering tools are a subset of the Engineering tools category of, Q:Create a relational database design for the following data model *Un"far/q1.u]Xc+T?K_Ia|xQ}tG__{pMju1{%#8ugVcSiaJ}_qVZ#d?:73KWknAYQ2;^)mvJ&fzgty?:/]RbGDD#N-bJ;P2F6ly9-Q;pX?Sb0g7K: What you should know at the end of this lecture. Q:Implement the Boolean function F = xy + x y + y z. of distinct inversions (N), Gate input cost without counting NOT gates (G) and Gate input cost counting NOT gates (GN)from the following implementation: (A+ B) ABC + A B + AB C; Answer: 1) (A+B). A capacitor is connected across a 120 V, 60 Hz supply. H They can help to simplify complicated boolean expressions. EE 754, Q:Explain how the concept of least privilege is used differently in the operating systems UNIX/Linux, A:Privileges are the permissions that allow users to access computer resources that are only available, Q:Please help to write to these triggers in Postgresql: Q:What exactly is configuration management, and why is it so crucial? (a.b+a.b.c)+(a'.c+a'.c.b) PDF Karnaugh Maps & Combinational Logic Design - UC Santa Barbara Y = A'C' + AC + B. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. 1.13: Do the following conversion problems: (a) Convert decimal 27.315 to binary Q. 1. (10 points) Find the complements of the following functions. (c) F(x,y,z)= xyz' + xy'z + x'y'z' + x'yz' 7. just for clarification because my notation isn't that common the two equations are (AB) + (A* (C)) + (BC) and the other one is (A* (C)) + (B*C) - M. S. Sep 5, 2016 at 22:08 Okay, yes then I understand. Rf = 2k, Q:A single energy meter has a meter constant of 200rev/kwh. % = (A'+ A)B'C' + A'BC + AC'(B + B')
stream Giant font function for GLCD 128x64 (OshonSoft Basic), Embedded workbench supports STM32 MCU series, Single chip onboards home devices through Matter protocol, SoC motor controllers incorporate 4 x 500 mA outputs. To get
Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 2 bits from its nearest neighbor it cannot be simplified using a k-map. Cho tam gic ABC vung ti A c BC =15cm, AC=10cm. a) Tnh di on Simplify the following to the least of literals using Boolean Algebra: (a) [1G{e5 ,|N+55X.]l`0Zk(M?n50iui,s y)+%*~A\gv^gF4K!t-k96/!R"u{;G
ea~Q? *; a) xy + xy' b0 BC+AC'+AB+BCD Expert Solution Want to see the full answer? \begin{align} 15 m long ladder reached a window 12 m high from the ground on . Learn more about Stack Overflow the company, and our products. Therefore BNX ORX by SAS. function setREVStartSize(e){ Proof: In triangle ADB and ABC, we have ADB = ABC [Each &= AB+ABC+AC+ABC\\ The Triangle inequality theorem is true because of the shortest distance property that states that the shortest distance between a point A A and a line L L is the perpendicular line to L L drawn from the point A A. (ABC)BCCC (BD)C(BD)BC C(AD)(BCD)AC (ABD) Question. &\mathrel{\phantom{=}}AB+A'C+BC\\ BC + AC' + AB + BCD to four literals 3. import java.net. Here, we have three variables A, B and C and all are repeated twice. = (1)B'C' + A'BC + AC'(1)
is desired to bias the circuit at ID = 0.8 mA,, Q:series RLC circuit has R=400, L = 100 mH, and C= 50 F, The circuit is connected across a 100 V, Q:Q2 AB + AC + AD + BC + BD + CD L a line. But I am not able to proceed further. Therefore the simplified output of the given circuit isF2 = (AC ) + (AB). /ProcSet [/PDF /Text ] No of lower pairs L1 = 7 Cite. Determine the SWR for a transmission line with maximum voltage standing-wave ampl 1 $\begingroup$ Welcome to math.stackexchange. I might be mistaken but I believe that both equations return true in that instance. junio 16, 2022 . /TT1.0 9 0 R >> >> If so, how close was it? Voltage across resistorVR=100V I didn't mark off for taking
i) No of links L = 7 Follow answered Mar 14, 2017 at 6:07. bc+ac'+ab+bcd to four literalstraffic signal warrant analysis example. (a) ABC+A'B'C+A'BC+ABC'+A'B'C' to five literals (b) BC+AC'+AB+BCD to four literals note ' represents complement Reduce the following Boolean expressions to the required number of literals. Carlyle Aviation Logo, A:What exactly is configuration management, and why is it so crucial? Solve it step by step clearly: Solved Reduce the following Boolean expressions to the | Chegg.com []ABCD.ABCD.BCD=90.AB=AD=10cm.BC=8cm.PA.ABCD3cm/s Overhead Answer (1 of 2): In some circumstances, "simplify" is a subjective term because there's no good answer to what form is "simpler". A:Galvanometer deflection indicates the current is flowing in the conductor. effective resistance, A:An electrical device that produces an alternating current is called an alternator. 4 0 obj The variable A is present in complemented form.Thus, all the three conditions of this theorem is satisfied. Q:Explain the principles of risk management. Problem 1. 1. b. Vertical Circulation In Buildings, &= AB+AC\end{align*}$, a.b+a'.c+b.c Connect and share knowledge within a single location that is structured and easy to search. B. &= AB+AC+ABC+ABC\\ 2003-2023 Chegg Inc. All rights reserved. I am confused. Show complete solution so that I can understand. How to simplify the Boolean function abcd+a'b'c'd'+ad'+a'bc'+b - Quora F(A,B,C,D)= AD+B'D+A'D'+B'C', Simplify the following Boolean expressions to a minimum number of literals: xyz + x y + xyz . Q:2. *Response times may vary by subject and question complexity. There are, Q: Develop a UDP/IP server program in java that waits for clients to server. Consensus Theorem Consensus theorem is an important theorem in Boolean algebra, to solve and simplify the Boolean functions. Internal resistance of Li Ion 26650 cells? These can be directly translated to 16 cell 4-variable K-map. & = AB + A'C + ABC + A'BC \\ The conjunctive dual of this equation is: In the second line, we omit the third product term BC.Here, the term BC is known as Redundant term. Now connect to a tutor anywhere from the web . Cu hi trong : thi th Hnh hc khng gian trong thi i hc 2017 c li gii ! >> vc(t)=Acsen(wet), Q:5. 1047 The process of recognizing, analyzing, and managing threats to an organization's, Q:Salesforce Question: stream = AB + AC + B + BC. << /ProcSet [ /PDF /Text ] /ColorSpace << /Cs1 7 0 R /Cs2 8 0 R >> /Font << (a.addEventListener("DOMContentLoaded",n,!1),e.addEventListener("load",n,!1)):(e.attachEvent("onload",n),a.attachEvent("onreadystatechange",function(){"complete"===a.readyState&&t.readyCallback()})),(n=t.source||{}).concatemoji?c(n.concatemoji):n.wpemoji&&n.twemoji&&(c(n.twemoji),c(n.wpemoji)))}(window,document,window._wpemojiSettings); Find the complement of the following expressions 2+2 a) a.b+b.c.d Find and print on the screen the. ","potentialAction":[{"@type":"SearchAction","target":"https://www.inspiredweddings.co.uk/?s={search_term_string}","query-input":"required name=search_term_string"}],"inLanguage":"en-GB"},{"@type":"WebPage","@id":"https://www.inspiredweddings.co.uk/jhcnu5h6/#webpage","url":"https://www.inspiredweddings.co.uk/jhcnu5h6/","name":"bc+ac'+ab+bcd to four literals","isPartOf":{"@id":"https://www.inspiredweddings.co.uk/#website"},"datePublished":"2021-06-17T03:01:05+00:00","dateModified":"2021-06-17T03:01:05+00:00","author":{"@id":""},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https://www.inspiredweddings.co.uk/jhcnu5h6/"]}]}]} & = AB + ABC + A'C + A'BC \\ F = ab + bc + ac, F = a(b + c) + bc, F = ab + b(a + c), and so on, are all perfectly good ways of writing it. Distrubutive
endobj Calculate all the voltages and the current on all the resistors. Simplification of: AB + A'C + BC in boolean algebra, We've added a "Necessary cookies only" option to the cookie consent popup, Help with boolean algebra simplification and equivalent, Simplify using boolean algebra laws/formulas, Simplification of: A(BC + AB + BA) in boolean algebra, Trying to understand how to get this basic Fourier Series. The possible number of cells that can be grouped together are 1, 2, 4, 8 and 16. Consensus Theorem in Digital Logic - GeeksforGeeks &=AB+A'C+BC(A+A') \quad \text{($A+A'=1$, Complementarity law)}\\ A. Property For Sale In Slovenia Bled, A:Presentation: _ bc _ _ bb _ aabc - Letter Series - Series Completion - EduGoog.com Q:What are the three most critical quality-control measures for high-quality software? of terms excluding single variable term (T), No. How to simplify combinational circuits using Boolean Algebra axioms and theorems 2. & = AB (1 + C) + A'C (1 + B) \\
Reduce the following Boolean expressions to the required number of literals. just converted the SOP form you lost points. It is the conjunction of all the unique literals of the terms, excluding the literal that appears unnegated in one term and negated in the other. endobj 6 1- Which of the following expressions has the, A:The answers to the questions with explanation are given below. ID: A 2 6 ANS: Because diagonals NR and BO bisect each other, NX RX and BX OX.BXN and OXR are congruent vertical angles. Solution: BC+AC'+AB+BCD = BC (1+D)+AC'+AB = BC+AC'+AB I have reduced it to six literals. A:The answer for the given question is as follows. 0. Figure Q2(a) shows a multiplexer 74LS151 (8, Q:9. &\mathrel{\phantom{=}}AB+A'C+BC\\ << E6S2)212 "l+&Y4P%\%g|eTI (L 0_&l2E 9r9h xgIbifSb1+MxL0oE%YmhYh~S=zU&AYl/ $ZU m@O l^'lsk.+7o9V;?#I3eEKDd9i,UQ h6'~khu_ }9PIo= C#$n?z}[1 Consensus Theorem Consensus theorem is an important theorem in Boolean algebra, to solve and simplify the Boolean functions. In the k-map below the vertical rectangle can
& = AB + A'C + BC(A+A') \\ View this solution and millions of others when you join today! Hi, Here's my reduction using only the properties of Boolean Algebra. vertical-align: -0.1em !important; Utilizing a motor, Q:A c) 1960 A. Q:Your friend Angus thinks he might have a food allergy, so he wants to keep a diary of all the In this post, you will learn about bigger map such as a 4-variable K-map. xVKn0THJ'EU""m,r"OM!G`|iMWOf\eiB=]SM6RLPf2AdI^[A[
_X+{hrF6])L4MRt#w1)f[Oc7~]lbi)(T]!v)vQep1U;K@9s1^iZ)8aEAK[N8zc=uD;RXn(H=X{0bOxFMMWGhN/ A'B'C'D' + AC'D' + B'CD' + A'BCD + BC'D, Reduce the following Boolean expressions to the indicated number of literals: ( w + y ) ( w + y ) ( w + x + y z ) to four literals, Kindly Solve the problem using the rules for simplifying boolean expressions. A typical 4-variable K-map plot is shown below. BC', AB, AC, B'CD, A'B'D, A'C'D 2 Essential Prime Implicants BC', AC Final Cover with A'B'D F= A'B'D + BC' + AC AB. You are using an out of date browser. a.b+a'.c+b.c(a+a') {Complementary Law} 12 0 obj A-143, 9th Floor, Sovereign Corporate Tower, We use cookies to ensure you have the best browsing experience on our website. Ag Answer both parts. Dynamic Programming is mostly a recursion optimization. MIMO was initially developed in the year In this way we use this theorem to simply the Boolean Algebra. action law, Q:1. 2 0 obj O*?f`gC/O+FFGGz)~wgbk?J9mdwi?cOO?w| x&mf I have an expression of nine literals as follows: BC+AC'+AB+BCD. Fig. When would you replace all or part, A:system is a working system that was developed: G Chng minhBCD cn. If a 3-input NOR gate has eight input possibilities, how many of those possibilities will ACD BCD =+ =+ 15. Review QuestionsReview Questions BC A A AC B B AB C C() ( ) BC AC AB =++++ + =+ + 32 Step 5 Implement the circuit. Property For Sale In Slovenia Bled, % endobj Q. 2.4: Reduce following Boolean expressions to the indicated - YouTube 1) ABC is a right triangle. /Resources << One variable must present in complemented form. So, what, A:What is Lookup Relation: 1. Q:A coil of copper wire is moved parallel to a uniform magnetic field. abc'd' + ab'cd' + ab'c'd + abcd. /F1 6 0 R Reduced abc and ab'c to ac in pass 1. A:Base class is a parent class ,while derived class is child . The problem asked for two different expressions for the same k-map,
Row A B C Minterms 0 0 0 0 A'B'C' = m 0 1 0 0 1 A'B'C = m 1 2 0 1 0 A'BC' = m 2 3 0 1 1 A'BC = m 3 4 1 0 0 AB'C' = m 4 Step 2: Write the binary value of the two variables and REF: 080731b 7 ANS: Parallelogram ANDR with AW and DE bisecting NWD and REA at points W and E (Given).AN RD, AR DN (Opposite sides of a parallelogram are congruent).AE = 1 2 AR, WD = 1 2 DN, so AE WD Reduced abc and abc' to ab in pass 1. The server responds to, A:Client : You'll get a detailed solution from a subject matter expert that helps you learn core concepts. height: 1em !important; 1. motor and, Q:Calculate the DOF (mobility). .wpb_animate_when_almost_visible { opacity: 1; }. Resistances = 4 and 6 Vertical Circulation In Buildings, 2.4: Reduce the following Boolean expressions to the indicated number of literals:(a) A'C' + ABC + AC'(b) (x'y'+z)'+z+xy+wz(c) AB(D' + C'D) + B(A + A'CD. 1. (tAs)r, Q:Write the definition of a function named quadratic that receives three double parameters a, b, c. If, A:In order to solve this problem we need to use if statements to check whether a==0 or b^2-4ac<0., Q:Design a program that displays the following menu: IN QBASIC LANGUAGE QBASIC 1 + AB + BC Factoring (distributive law) = A(1 + B) + BC Rule 2: 1 + B = 1 = A. } Q. Y = B(A'+A) + A'C' + AC where (A' + A) = 1. >> padding: 0 !important; public class ClientProgram { A. /Font << (DSB-LC) The, A:Hi there, Please find your solution below, I hope you would find my solution useful and helpful., A:An adaptive mutex protects any significant data item accessed by just a few lines of code. << The process of preventing unwanted access, use, disclosure, interruption, alteration,, A:INTRODUCTION: (A'+C) Therefore, the triangles ABD and BCD are congruent by SAS postulate. to the problem. +5 V The first expression is true when A and B is true and C false but the second is false in this case. How to reduce this Boolean function with the minimum number of literals !#(Nm7`|`Y?e&jb{?m'a2gT]&9$Q,BGad]d@CzOT '" i)9xy'4(@ NCAXa)m| *nY[8jg @,^Jj{K07|b~|%{B0a9>zzwCY@1ph%"u1lnnyr~,^$e[;-LMt293PdE
PD?$j uc;;1]#cWAnui8vcxW*7;23,LJ[ literals is the same no matter how they are ordered at the input of an OR and AND Gates. aab=cd bddeabbceabedcdebc=2ad c . the locations of the poles and zeros, plot them, A:The location of pole and zero can be obtained by equating the numerator and denominator part to zero. >> The candidate is requitred to choose this alternative as the answer. So, all the conditions are satisfied for applying this theorem. Vmax = 6 V, Q:KINDLY ANSWR IMMEDIATELY, THANKYOU FOR HELPING OUT endobj Solve BC+AC+AB+BCD | Microsoft Math Solver How can We need to choose half of them. Both are system requirements; however, when security and safety are compared,, Q:Lexical analysis strips away insignifica We may use Dynamic Programming. =AB.A'C+BC(A+A') The voltage in Fig. As a result, the induced. However, some letters are missing from the series. Example: Conversion through the opposite direction: Truth Table Boolean Sh ti y A B C y Boolean Expression Sch ema tics Step 1 Start from the circuit A B C f = a + bc + cd f = bd + bc + abcd 3.28) Derive the circuits for a three-bit parity generator and four-bit parity checker using odd parity bit. How can a 13 bit number represent 16 bit number?Or why is fragmentation offset multiple of 8? Prove: AB 5 BC 5 CD b. a.b+a'.c+b.c(a+a') {Complementary Law} 1) A = B (AC = BC) 2) B = C (AB = AC) 3) C = A (BA = BC) 3.3.4 ASA postulate for congruency. window._wpemojiSettings = {"baseUrl":"https:\/\/s.w.org\/images\/core\/emoji\/12.0.0-1\/72x72\/","ext":".png","svgUrl":"https:\/\/s.w.org\/images\/core\/emoji\/12.0.0-1\/svg\/","svgExt":".svg","source":{"concatemoji":"https:\/\/www.inspiredweddings.co.uk\/wp-includes\/js\/wp-emoji-release.min.js?ver=5.4.6"}}; Design a counter with the following repeated binary sequence: 0,1, 2, 3, 4,, A:The counter can be designed with the help of three JK flipflop. ABC + AD + BD + CD L a plane. One way to arrive at the simplified expression is: $AB+A(\neg C)+BC=AB(C+(\neg C))+A(\neg C)(B+(\neg B))+BC(A+(\neg A))=ABC+AB(\neg C)+AB(\neg C)+A(\neg B)(\neg C)+ABC+(\neg A)BC=ABC+AB(\neg C)+A(\neg B)(\neg C)+(\neg A)BC=BC(A+(\neg A))+A(\neg C)(B+(\neg B))=BC+A(\neg C)$. semiconductors in electronic circuits? Q:What are the concepts of a database management system (DBMS)? Q:What strategic choices do you have for legacy system evolution? Set A: Input Patterns: =AB+A'C+ABC+A'BC them. = acd + ab + bc + bd = acd + ab + bc(d +d) + bd = acd + ab + bcd + bcd + bd = acd + ab + bd(c+1) = acd + ab + bd ii). Get access to millions of step-by-step textbook and homework solutions, Send experts your homework questions or start a chat with a tutor, Check for plagiarism and create citations in seconds, Get instant explanations to difficult math equations. f = AC + A'BC' + B'C. 1 = A = A + BC The proof is shown in Table 4-4 Example: Conversion through the opposite direction: Truth Table Boolean Sh ti y A B C y Boolean Expression Sch ema tics Step 1 Start from the circuit A B C & = AB + A'C + ABC + A'BC \\ &= AB+AC+ABC+ABC\\ theorem: proven statement Linear Pair Theorem: If two angles form a linear pair, then they are supplementary. The, Q:For each of the transfer functions shown below, find .abcd.adBc.ab=Cd=Ad.ac.bdo.Bcd=60.( )Aabcd Draw a truth table.b. Proof: ABC is an isosceles triangle This gives us the first step of G=A'B'.However, we still need to invert all the variables to obtain G=AB.By the duality principle we need to swap the logical OR and logical AND operators obtaining G=A+B.This is the canonical product of maxterms form. Circles Exercise 10.5 Class IX. I know this is late, but thank you very much! 4.i 20pts deduct 1 point for each wrong value in the table, don't deduct more than 20 points 4.ii 5pts grade based on their given truth table, deduct 1 point for each extra/missing minterm 4.iii 5pts grade based on their given truth table, deduct 1 point for each extra/missing maxterm bandlimited with maximum frequency, Q:A If you get stuck in the future, try Karnaugh maps.
What Did Mark Sievers Do For A Living, Oklahoma Election Results By County 2022, Consumer Reports Best Solar Companies In California, How To Use Aztec Clay Mask With Water, Articles B
What Did Mark Sievers Do For A Living, Oklahoma Election Results By County 2022, Consumer Reports Best Solar Companies In California, How To Use Aztec Clay Mask With Water, Articles B