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Graham Kemp
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You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Stanford?) should allow this, otherwise you might require the premise to be reiterated into the assumptions scope.


Edit: Ah,I thought this looked familiar.   It is indeed exercise 4-4 of the Standford Logic online course.   There is a "Show Answer" button there, which... does pretty much give the above result.

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Stanford?) should allow this, otherwise you might require the premise to be reiterated into the assumptions scope.

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Stanford?) should allow this, otherwise you might require the premise to be reiterated into the assumptions scope.


Edit: Ah,I thought this looked familiar.   It is indeed exercise 4-4 of the Standford Logic online course.   There is a "Show Answer" button there, which... does pretty much give the above result.

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Graham Kemp
  • 2.4k
  • 8
  • 14

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (StafordStanford?) should allow this, otherwise you might require you to reiterate the premise to be reiterated into the assumption'sassumptions scope, but otherwise that is all you need.

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Staford?) might require you to reiterate the premise into the assumption's scope, but otherwise that is all you need.

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Stanford?) should allow this, otherwise you might require the premise to be reiterated into the assumptions scope.

Source Link
Graham Kemp
  • 2.4k
  • 8
  • 14

You already know p → q. You just need to deduce q → q, enabling you to eliminate the disjunction to conclude q as desired. As: p ˅ q, p → q, q → q Ͱ q

1.|  p → q       : premise
2.|_ m → (p ˅ q) : premise
3.|   |_ m       : assumption
4.|   |  p ˅ q   : conditional elimination (2,3)
5.|   |   |_ q   : assumption
6.|   |  q → q   : conditional introduction (5-5)
7.|   |  q       : disjunction elimination (4,1,6)
8.|  m → q       : conditional introduction (3-7)

The proof writer you are using (Staford?) might require you to reiterate the premise into the assumption's scope, but otherwise that is all you need.