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Today’s Lecture 4/22/10
9.3
--More Practice with Direct Proofs for Pred Logic
9.4
--Intro to QN, RAA, CP for Pred Logic
Announcements
-- Final Exam on May 11th (now’s the time to start
studying)!
-- Next Tues is the deadline to turn in any late homework
-- Homework:
- Ex 9.4 pg. 469 Part A (1-10 All, 14, 15, 16).
[note that for #4 – the answer is in the back of the book – there is no need for a DN move. The last edition of our text required this, but it has since expanded the QN rule. In short, the DN
annotation is a mistake].
Announcements
Recommendation for the Homework:
-For problems 1-5, 8, and 16 use direct proof
-For problems 6,7,9, 14 use conditional proof.
-For problem 10 use RAA; for problem 15 use conditional proof but also use RAA to derive the consequent.
Some More Tips
-- Always employ EI before UI
-- If the conclusion is a universally quantified statement, derive an instance of it and apply UG to the instance.
#10
1. (y)(~Py ! ~Ly)
2. Lc " Ld # Pd " Pc
3. ~Pc ! ~Lc 1, UI
4. Lc ! Pc 3, Cont
5. ~Pd ! ~Ld 1, UI
6. Ld ! Pd 5, Cont
7. Pc " Pd 2,4,6 CD
8. Pd " Pc 7, Com
#12
1. (z)[Uz ! (Kz " Sz)]
2. (z)Uz
3. ($z)~Sz # ($z)Kz
4. ~Sa 3, EI
5. Ua ! (Ka " Sa) 1, UI
6. Ua 2, UI
7. Ka " Sa 5,6 MP
8. Ka 7,4 DS
9. ($z)Kz 8, EG
#14
1. (x)[Cx ! (Dx • ($y)Ey)]
2. ~Db # ($x)~Cx
3. Cb ! (Db • ($y)Ey) 1, UI
4. ~Db " ~($y)Ey 2, Add
5. ~(Db • ($y)Ey) 4, DeM
6. ~Cb 3,5 MT
7. ($x)~Cx 6, EG
#16
1. (z)~[~(x)Jx " ~Kz] # Jc • Kc
2. ~[~(x)Jx " ~Kc] 1, UI
3. ~~(x)Jx • ~~Kc 2, DeM
4. (x)Jx • Kc 3, DN DN
5. (x)Jx 4, Simp
6. Jc 5, UI
7. Kc 4, Simp
8. Jc • Kc 6,7 Conj
#18
1. (x)[(Bx ! (z)Az) ! ~P]
2. ($x)~Bx # ~P
3. ~Ba 2, EI
4. (Ba ! (z)Az) ! ~P 1, UI
5. (~Ba " (z)Az) ! ~P 4, MI
6. ~Ba " (z)Az 3, Add
7. ~P 5,6 MP
#20
1. (x)[(Sx • ~(z)Rz) ! Nd]
2. (x)~Nx
3. ($x)Sx # Rc
4. Sa 3, EI
5. (Sa • ~(z)Rz) ! Nd 1, UI
6. ~Nd 2, UI
7. ~(Sa • ~(z)Rz) 5,6 MT
8. ~Sa " ~~(z)Rz 7, DeM
9. ~~Sa 4, DN
10. ~~(z)Rz 8,9 DS
11. (z)Rz 10, DN
12. Rc 11, UI
#5
1. (x)(Jx ! ~Ex)
2. ( $x)(Jx " Jd) # ($y)(Ey ! ~Ed)
3. Ja " Jd 2, EI
4. Ja ! ~Ea 1, UI
5. Jd ! ~Ed 1, UI
6. ~Ea " ~Ed 3,4,5 CD
7. Ea ! ~Ed 6, MI
8. ($y)(Ey ! ~Ed) 7, EG
#6
1. (x)(Lx ! Mx) ! (x)(Nx ! Lx)
2. (x)~Lx # (x)~Nx
3. ~La 2, UI
4. ~La " Ma 3, Add
5. La ! Ma 4, MI
6. (x)(Lx ! Mx) 5, UG
7. (x)(Nx ! Lx) 1, 6 MP
8. Na ! La 7, UI
9. ~Na 8,3 MT
10. (x)~Nx 9, UG
#7
1. (x)(Sx ! Tx)
2. ($y)(Ry • ~Ty) # ($z)(Rz • ~Sz)
3. Ra • ~Ta 2, EI
4. Sa ! Ta 1, UI
5. ~Ta 3, Simp
6. ~Sa 4,5 MT
7. Ra 3, Simp
8. Ra • ~Sa 7,6 Conj
9. ($z)(Rz • ~Sz) 8, EG
#8
1. (x)(Bx ! Cx)
2. (x)(Ax ! Bx)
3. (x)(Cx ! Dx)
4. ($x)~Dx #($x)~Ax
5. ~Da 4, EI
6. Ca ! Da 3, UI
7. Aa ! Ba 2, UI
8. Ba ! Ca 1, UI
9. ~Ca 6,5 MT
10. ~Ba 8,9 MT
11. ~Aa 7, 10 MT
12. ($x)~Ax 11, EG
#9
1. (x)(Rx % Sx) # (x)(Rx ! Sx) • (x)(Sx ! Rx)
2. Ra % Sa 1, UI
3. (Ra ! Sa) • (Sa ! Ra) 2, ME
4. (Ra ! Sa) 3, Simp
5. (x)(Rx ! Sx) 4, UG
6. (Sa ! Ra) 3, Simp
7. (x)(Sx ! Rx) 6, UG
8. (x)(Rx ! Sx) • (x)(Sx ! Rx) 5,7 Conj
#10
1. (x)[(Bx " Ax) % Cx]
2. (x) ~Cx # (x)(Ax % Bx)
3. (Ba " Aa) % Ca 1, UI
4. [(Ba " Aa) ! Ca] • [Ca ! (Ba " Aa)] 3, ME
5. ~Ca 2, UI
6. (Ba " Aa) ! Ca 4, Simp
7. ~(Ba " Aa) 5,6 MT
8. ~Ba • ~Aa 7, DeM
9. ~Aa 8, Simp
10. ~Aa " Ba 9, Add
11. Aa ! Ba 10, MI
12. ~Ba 8, Simp
13. ~Ba " Aa 12, Add
14. Ba ! Aa 13, MI
15. (Aa ! Ba) • (Ba ! Aa) 11, 14 Conj
16. (Aa % Ba) 15, ME
17. (x)(Ax % Bx) 16, UG
#11
1. (x)(Dx ! ~Kx)
2. ($x)(Ex • Hx)
3. (x)(Hx ! Dx)
4. (x)(Jx ! Kx) # ($x)(Ex • ~Jx)
5. Ea • Ha 2, EI
6. Ha ! Da 3, UI
7. Ha 5, Simp
8. Da 6,7 MP
9. Da ! ~Ka 1, UI
10. ~Ka 8,9 MP
11. Ja !Ka 4, UI
12. ~Ja 10,11 MT
13. Ea 5, Simp
14. Ea • ~Ja 13, 12 Conj
15. ($x)(Ex • ~Jx) 14, EG
#12
1. (x)[Fx % (Hx • ~(y)Gy)]
2. ($x)~Fx
3. (z)Hz # Gc
4. ~Fa 2, EI
5. Fa %(Ha • ~(y)Gy) 1,UI
6. [Fa !(Ha • ~(y)Gy)] • [(Ha • ~(y)Gy) ! Fa] 5, ME
7. (Ha • ~(y)Gy) ! Fa 6, Simp
8. ~(Ha • ~(y)Gy) 4,7 MT
9. ~Ha " ~~(y)Gy 8 DeM
10. ~~Ha 3 UI, DN
11. (y)Gy 9, 10 DS, DN
12. Gc 11, UI
#13
1. (x)[Bx ! (Cx • Dx)]
2. ($x)Bx # ($x)~(~Cx " ~Dx)
3. Ba 2, EI
4. Ba ! (Ca • Da) 2, UI
5. Ca • Da 3,4 MP
6. ~~Ca • ~~Da 5, DN DN
7. ~(~Ca " ~Da) 6, DeM
8. ($x)~(~Cx " ~Dx) 7, EG
#14
1. (x)[Mx ! ($y)(Ny • Px)]
2. (x)(Nx ! ~G)
3. ($x)Mx # ~G
4. Ma 3, EI
5. Ma ! ($y)(Ny • Pa) I, UI
6. ($y)(Ny • Pa) 4,5 MP
7. Nb • Pa 6, EI
8. Nb 7, Simp
9. Nb ! ~G 2, UI
10. ~G 8,9 MP
#15
1. (x)[Rx ! (Sx " (y)Ty)]
2. (x)(Rx ! Sx) ! Pb
3. ~(y)Ty # Pb
4. Ra ! (Sa " (y)Ty) 1, UI
5. ~Ra " (Sa " (y)Ty) 4, MI
6. (~Ra " Sa) " (y)Ty 5, As
7. ~Ra " Sa 3,6 DS
8. Ra ! Sa 7 MI
9. (x)(Rx ! Sx) 8, UG
10. Pb 2,9 MP
An Equivalence Rule: QN
Consider:
“Something is red”. Symbolically, we can say, ($x)Rx.
This is equivalent to saying, “ it’s not the case that everything is not red”. Symbolically: ~(x)~Rx.
An Equivalence Rule: QN
Consider:
“Something is red”. Symbolically, we can say, ($x)Rx.
This is equivalent to saying, “ it’s not the case that everything is not red”. Symbolically: ~(x)~Rx.
[Everything is not red? No. For something is red].
An Equivalence Rule: QN
Consider:
“Something is not red”. ($x)~Rx.
This is equivalent to saying, “it’s not the case that everything is red”. ~(x)Rx
An Equivalence Rule: QN
Consider:
“Everything is red”. (x)Rx.
This is like saying, “it’s not the case that something is not red. ~($x)~Rx
An Equivalence Rule: QN
Consider:
“Everything is red”. (x)Rx.
This is like saying, “it’s not the case that something is not red. ~($x)~Rx
[Something is not red? No. For everything is red].
An Equivalence Rule: QN
Consider:
“Everything is not red”. (x)~Rx.
This is like saying, “it’s not the case that something is red”. ~($x)Rx
An Equivalence Rule: QN
The statements in each aforementioned pair logically imply one another. If one is true, the other must be true. They are, after all, just different ways of saying the same thing.
An Equivalence Rule: QN
The statements in each aforementioned pair logically imply one another. If one is true, the other must be true. They are, after all, just different ways of saying the same thing.
These statements illustrate the equivalence rule of Quantifier Negation (QN). Below are the four different forms:
($x)P is equiv. to ~(x)~P
($x)~P is equiv to ~(x)P
(x)P is equiv to ~($x)~P
(x)~P is equiv. to ~($x)P
An Equivalence Rule: QN
QN can be applied to parts of lines. So we can have inferences such as the following:
1. (x)~Hx ! (y)Ky
2. ~($x)Hx ! (y)Ky 1, QN
1. (y)By ! ~(x)Ax
2. (y)By ! ($x)~Ax 1, QN
Another Tip
As a general rule, you may find it helpful to apply QN to a line that contains a negated quantifier [e.g. ~($x), ~(x)]. This can set you up for a UI or EI move.
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
9. ~Ra 7,8 MT
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
9. ~Ra 7,8 MT
10. ~~Aa 6, Simp
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
9. ~Ra 7,8 MT
10. ~~Aa 6, Simp
11. Aa 10, DN
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
9. ~Ra 7,8 MT
10. ~~Aa 6, Simp
11. Aa 10, DN
12. Aa • ~Ra 11, 9 Conj
Practice Proof -- Direct
1. ~(x)(Ax ! Mx)
2. (x)(Rx ! Mx) # ($x)(Ax • ~Rx)
3. ($x)~(Ax ! Mx) 1, QN
4. ~(Aa ! Ma) 3, EI
5. ~(~Aa " Ma) 4, MI
6. ~~Aa • ~Ma 5, DeM
7. ~Ma 6, Simp
8. Ra ! Ma 2, UI
9. ~Ra 7,8 MT
10. ~~Aa 6, Simp
11. Aa 10, DN
12. Aa • ~Ra 11, 9 Conj
13. ($x)(Ax • ~Rx) 12 EG
RAA Proofs for Predicate Logic
Note well that with RAA proofs (and conditional proofs), we cannot universally generalize from a constant that appears in an unboxed assumption.
If we were permitted to do this, then it becomes possible to show that clearly invalid arguments are valid. But it’s impossible to show that an invalid argument is valid (any proof that shows an invalid argument to be valid is mistaken). Thus we’re not permitted to univ. generalize from a constant that appears in an unboxed assumption.
There is no such problematic consequence though if we universally generalize from a constant that appears in a boxed assumption.
Universal Generalization (UG)
A Brief Summary of Universal Generalization (UG):
A line in a proof follows from some previous line via UG if and only if the line that follows is a universally quantified statement, and the line from which it follows is an instance of it (the universally quantified statement), and where the constant in the instance does not occur in a premise of the argument, a previous line derived by EI, in the universally quantified statement itself, nor in an unboxed (un-discharged) assumption.
Another Tip
As a general rule, it is oftentimes helpful to construct an RAA proof when the conclusion to be proved is an existentially quantified statement.
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
10. Sb 8,9 MP
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
10. Sb 8,9 MP
11. ~Sb 4, UI
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
10. Sb 8,9 MP
11. ~Sb 4, UI
12. Sb • ~Sb 10, 11 Conj
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
10. Sb 8,9 MP
11. ~Sb 4, UI
12. Sb • ~Sb 10, 11 Conj
13. ($x)Sx 3-12 RAA
RAA Proofs for Predicate Logic
Use an RAA proof to show the following argument to be valid:
1. (x)(Px ! Sx)
2. Pa " Pb # ($x)Sx
3. ~($x)Sx Assume for RAA
4. (x)~Sx 3, QN
5. Pa ! Sa 1, UI
6. ~Sa 4, UI
7. ~Pa 5,6MT
8. Pb 2,7 DS
9. Pb ! Sb 1, UI
10. Sb 8,9 MP
11. ~Sb 4, UI
12. Sb • ~Sb 10, 11 Conj
13. ($x)Sx 3-12 RAA
Another Tip
If the conclusion is a universally quantified statement that contains a conditional, use CP to derive the conditional and then apply UG
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
7. Ha 3,5 MP
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
7. Ha 3,5 MP
8. Ga • Ha 6,7 Conj
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
7. Ha 3,5 MP
8. Ga • Ha 6,7 Conj
9. Fa ! (Ga • Ha) 3-8 CP
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
7. Ha 3,5 MP
8. Ga • Ha 6,7 Conj
9. Fa ! (Ga • Ha) 3-8 CP
CP for Predicate Logic
1. (x)(Fx ! Gx)
2. (x)(Fx ! Hx) # (x)[Fx ! (Gx • Hx)]
3. Fa Assume for CP
4. Fa ! Ga 1, UI
5. Fa ! Ha 2, UI
6. Ga 3,4 MP
7. Ha 3,5 MP
8. Ga • Ha 6,7 Conj
9. Fa ! (Ga • Ha) 3-8 CP
10. (x)[Fx ! (Gx • Hx)] 9, UG
Ex 9.4 pg. 469-470 Part A (1-10 All, 14, 15, 16).
-For problems 1-5, 8, and 16 use direct proof
-For problems 6,7,9, 14 use conditional proof.
-For problem 10 use RAA; for problem 15 use conditional proof but also use RAA to derive the consequent.
Possible answers are on following slides:
#5
1. ($y)Hy ! ($y)Jy
2. (y)~Jy # ~Ha
3. ~($y)Jy 2, QN
4. ~($y)Hy 1,3 MT
5. (y)~Hy 4, QN
6. ~Ha 5, UI
#6
1. (z)[(Kz " Lz) ! Mz] # (z)(Lz ! Mz)
2. La Assume for CP
3. (Ka " La) ! Ma 1, UI
4. Ka " La 2, Add
5. Ma 3,4 MP
6. La ! Ma 2-5 CP
7. (z)(Lz ! Mz) 6, UG
#7
1. (x)(Nx ! Ox) # ~(x)Ox ! ~(x)Nx
2. ~(x)Ox Assume CP
3. ($x)~Ox 2, QN
4. ~Oa 3, EI
5. Na ! Oa 1, UI
6. ~Na 5,4 MT
7. ($x)~Nx 6, EG
8. ~(x)Nx 7, QN
9. ~(x)Ox ! ~(x)Nx 2-8 CP
#8
1. ~($x)~Px
2. ~($y)Sy " ~(x)Px # ~Sd
3. (x)Px 1, QN
4. ~~(x)Px 3, DN
5. ~($y)Sy 2,4 DS
6. (y)~Sy 5, QN
7. ~Sd 6, UI
#9
1. (x)~Rx ! ($x)~~Tx # (x)~Tx ! ($x)Rx
2. (x)~Tx Assume CP
3. ~($x)Tx 2, QN
4. (x)~Rx ! ($x)Tx 1, DN
5.~(x)~Rx 3,4 MT
6. ($x)Rx 5, QN
7. (x)~Tx ! ($x)Rx 2-6 CP
#10
1. (x)(Ax ! ~Bx)
2. (y)Ay # (z)~Bz
3. ~(z)~Bz Assume RAA
4. ($z)Bz 3, QN
5. Ba 4, EI
6. Aa ! ~Ba 6, UI
7. Aa 2, UI
8. ~Ba 6,7 MP
9. Ba • ~Ba 5,8 Conj
10. (z)~Bz 3-9 RAA
#14
1. ($x)[Fx • (y)(Gy ! Hx)]
2. (x)[Fx ! (y)(By ! ~Hx)] # (x)(Gx ! ~Bx)
3. Ga Assume CP
4. Fb • (y)(Gy ! Hb) 1, EI
5. Fb 4, Simp
6. (y)(Gy ! Hb) 4, Simp
7. Fb ! (y)(By ! ~Hb) 2, UI
8. (y)(By ! ~Hb) 5, 7 MP
9. Ga ! Hb 6, UI
10. Hb 3,9 MP
11. Ba ! ~Hb 8, UI
12. ~~Hb 10, DN
13. ~Ba 11, 12 MT
14. Ga ! ~Ba 3-13 CP
15. (x)(Gx ! ~Bx) 14, UG
#15
1. (x)[Dx ! ($y)(Fy • Gy)] # (x)~Fx ! ~($y)Dy
2. (x)~Fx Assume CP
3. ($y)Dy Assume RAA
4. Da 3, EI
5. Da ! ($y)(Fy • Gy) 1, UI
6. ($y)(Fy • Gy) 4,5 MP
7. Fb • Gb 6, EI
8. ~Fb 2, UI
9. Fb 7, Simp
10. ~Fb • Fb 8,9 Conj
11. ~($y)Dy 3-10 RAA
12. (x)~Fx ! ~($y)Dy 2-11 CP