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NPP               Number System, Boolean Algebra and Logic Circuits              195


                      F is a Boolean function which is the prod-  ì`§OH$ F =  (A +  B ) (A.  +  B ) _| Xmo `moJ  (A +
                  uct of two sums (A + B) and (A +  B ). Other ex-  B) VWm (A +  B ) h¢ Ÿ& BZH$m JwUZ\$b {b`m h¡ & POS
                  amples of POS form are:
                                                              ê$n Ho$ AÝ` CXmhaU Bg àH$ma h¡…
                                         Y =  (A +  B +  C ) (A.  +  B +  C )
                                         Q =  (X +  Y ) (X.  +  Y ) (X.  +  Y )

                                         F = (A + B+ C + D ) (A.  + B + C + D ) (A.  +  B + C+  ) D
                      A canonical POS form is that in which each  EH$ Ho$Zmo{ZH$b POS ê$n _| g^r `moJm| _| g_mZ
                  sum contain equal number of variables:      g§»`m _| am{e`m± hmoVr h¢…
                                          e.g. (A +  B +  C ) (A.  +  B +  C ) (A.  +  B +  C )
                      is a canonical POS form. But the following  EH$ Ho$Zmo{ZH$b POS ñdê$n h¡ VWm {ZåZ ì`§OH$
                  is not a canonical POS form :
                                                              Ho$Zmo{ZH$b POS Zht h¡ …
                                        F =  (A + B +  C +  D ) (A.  +  B + C + D ) (A.  + B +  ) C
                       Problem 3.49   NPP                          àíZ 3.49
                      State whether the following expressions     ~VmB`o {H$ {ZåZ SOP h¢ `m POS:
                  are in SOP form or POS form:
                         (a) F =  (A +  B ) (A.  +  B ) (A.  +  B )  (b)  Q =  D . C . B . A  +  D . C . B . A  +  D . C . B . A

                         (c) F =    Z . Y . X  +  Y . X  +  Y . X  (d)  Y =  R . Q . P  +  Q . R  +  . P  R

                         (e) F =  (X +  Y ) (X.  +  Y )      (f)   P =  Z . F  +  Z . F  +  P . Z . F
                  Solution:                                   hc:
                      (a) POS                                 (b) SOP
                      (c) SOP                                 (d) SOP
                      (e) POS                                 (f) SOP.

                   3.19 Fundamental Product and Fun-          3.19 \$ÝS>m_|Q>b àmoS>ŠQ> VWm \§$S>m_|Q>b g_
                   damental Sum

                      Fundamental Product: “A  Fundamental        EH$ \§$S>m_|Q>b àmoS>ŠQ> dh hmoVm h¡ Omo Ma am{e`m|
                  Product is a product of binary variables which  Ho$ EH$ {deof _mZ Ho$ {bE "1" hmoVm h¡ VWm ~mH$s gmao
                  is equal to ‘1’ for the specified values of the vari-  _mZm| Ho$ {bE "0" hmoVm h¡ Ÿ&
                  ables and is equal to ‘0’ for all other values of
                  input variables.”
                      Consider two variables A and B. These vari-  _mZm {H$ A VWm B Xmo Ma am{e`m± h¢, VWm BgHo$
                  ables may have four sets of values as shown be-  Mma gå^d _mZ Bg àH$ma h¢…
                  low:
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