Q8.4a
Show that '~Ja&~Qa' can be derived on line 4.
(Show
QN
or
SD+ rules of replacement
.)
Justification: Sentence:
1 QN
1 NQ
1 NN
1 QQ
______
2
(%x)~(JxvQx)
(^x)~(JxvQx)
~(^x)(JxvQx)
____________
2 DN
2 DM
2 IM
2 ID
______
3
(^x)(~Jx&~Qx)
(^x)(~Jxv~Qx)
(%x)(~Jx&~Qx)
___________
3 ^I
3 ^E
3 %I
3 %E
______
4
~Jx&~Qx
(%x)(~Jx&~Qx)
~Ja&~Qa
____________