3 problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 problem-solving processes 3.1...
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3 Problem-solving processes
3.1 Aim and introductory remarks
3.2 Problem-solving processes: first elements
3.3 An example
3.4 The rules and the permissions and obligations
3.5 Answerable questions
3.6 Variants, extensions and comments
3 0
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3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
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3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
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3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
![Page 5: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/5.jpg)
3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
· empirical means (observation and experiment)
![Page 6: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/6.jpg)
3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
· empirical means (observation and experiment)
· + new available information (not originally seen as relevant)
(easy extension)
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3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
· empirical means (observation and experiment)
· + new available information (not originally seen as relevant)
(easy extension)
· + corrective and ampliative logics, handling inconsistency, . . .
includes forming new hypotheses
adaptive logics: control by conditions and marking definition
(easy extension)
![Page 8: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/8.jpg)
3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
· empirical means (observation and experiment)
· + new available information (not originally seen as relevant)
(easy extension)
· + corrective and ampliative logics, handling inconsistency, . . .
includes forming new hypotheses
adaptive logics: control by conditions and marking definition
(easy extension)
· + devise new empirical means: future research
(seems within reach)
![Page 9: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/9.jpg)
3.1 Aim and introductory remarks H
backbone of formal approach to problem solving
· aim: explication of problem solving processes (psps)
· backbone: solve {?{A, ∼A}} by deriving A or ∼A from Γ by CL
· empirical means (observation and experiment)
· + new available information (not originally seen as relevant)
(easy extension)
· + corrective and ampliative logics, handling inconsistency, . . .
includes forming new hypotheses
adaptive logics: control by conditions and marking definition
(easy extension)
· + devise new empirical means: future research
(seems within reach)
· + model-based reasoning, . . . : future research
H
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Plan H
given a logic (or a set of logics) L, we can handle the heuristics
(see previous lecture)
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Plan H
given a logic (or a set of logics) L, we can handle the heuristics
(see previous lecture)
viz. define the procedure
for solving {?{A, ∼A}} by deriving A or ∼A from Γ by L
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Plan H
given a logic (or a set of logics) L, we can handle the heuristics
(see previous lecture)
viz. define the procedure
for solving {?{A, ∼A}} by deriving A or ∼A from Γ by L
adaptive logics enable us to explicate the reasoning behind many psps
(see next lecture)
H
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Background H
• philosophy of science: Nickles, Meheus, Batens
• erotetic logic (varying on Wisniewski)
• logic · adaptive logics
· prospective dynamics
· procedures
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Background H
• philosophy of science: Nickles, Meheus, Batens
• erotetic logic (varying on Wisniewski)
• logic · adaptive logics
· prospective dynamics
· procedures
problem determined by (changing) constraints
· conditions on the solution
· methodological instructions / heuristics / examples
· certainties (conceptual system . . . )
H
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Formal approach H
formal but not logic with the usual connotations
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· psp (problem solving process) – success?
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· arbitrary sequence of applications of rules
· psp (problem solving process) – success?
· goal directed
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· arbitrary sequence of applications of rules
· infinite consequence set
· psp (problem solving process) – success?
· goal directed
· unique aim (possibly unspecified at outset)
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· arbitrary sequence of applications of rules
· infinite consequence set
· useless subsequences
· psp (problem solving process) – success?
· goal directed
· unique aim (possibly unspecified at outset)
· unsuccessful subsequences
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· arbitrary sequence of applications of rules
· infinite consequence set
· useless subsequences
· deductive
· psp (problem solving process) – success?
· goal directed
· unique aim (possibly unspecified at outset)
· unsuccessful subsequences
· also other forms of reasoning
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Formal approach H
formal but not logic with the usual connotations
· proofs – success
· arbitrary sequence of applications of rules
· infinite consequence set
· useless subsequences
· deductive
· CL
· psp (problem solving process) – success?
· goal directed
· unique aim (possibly unspecified at outset)
· unsuccessful subsequences
· also other forms of reasoning
· multiplicity of logics
H
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H
differences partly rely on confusion
· proof search is goal-directed process (and is a psp)
· proof search is not always successful
· no arbitrary sequences result of proof search
· proof search for one formula from given premises
(but set of problems solvable by certain means)
· unsuccessful subsequences in proof search
no ‘useless’ subsequences in goal-directed proofs
· that all logic is deductive (or is CL) is a plain prejudice
3.1 3
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3.2 Problem-solving processes: first elements H
terminology: psp refers to explicandum and to explicatum
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3.2 Problem-solving processes: first elements H
terminology: psp refers to explicandum and to explicatum
• psps contain unsuccessful subsequences
· justified at some point in the psp
· not justified any more at later point
· and vice versa
‘unsuccessful’ is a dynamic property
H
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H
• psps require prospective dynamics + derived problems
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H
• psps require prospective dynamics + derived problems
· prospective dynamics (previous lecture)
now breath first (better w.r.t. problems)
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H
• psps require prospective dynamics + derived problems
· prospective dynamics (previous lecture)
now breath first (better w.r.t. problems)
· derived problems:
{?{A, ∼A}} (problem). . .[B1, . . . , Bn] A (if B1, . . . , Bn true, then also A)
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H
• psps require prospective dynamics + derived problems
· prospective dynamics (previous lecture)
now breath first (better w.r.t. problems)
· derived problems:
{?{A, ∼A}} (problem). . .[B1, . . . , Bn] A (if B1, . . . , Bn true, then also A){?{B1, ∼B1}, . . . , ?{Bn, ∼Bn}} derived problem
H
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Lines occurring in a psp H
problem lines: problem = non-empty set of questions
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Lines occurring in a psp H
problem lines: problem = non-empty set of questions
declarative lines
· conditional: [B1, . . . , Bn] A
· unconditional: [∅] A, viz. A
H
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H
a stage of a psp: sequence of lines
a psp: chain of stages
next stage obtained by adding new line
marks may change (governed by marking definitions)
relation between stages governed by procedure
H
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rehearsal
· the complement of a formula
· a-formulas and b-formulas (a and b)
· formula analysing rules and condition analysing rules
· pp(A, B) (A is a positive part of B)
· the Prem rule
· EM, EM0 and Trans
· direct answer to a question / problem
H
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Specific rules H
Where {?{M, ∼M}} is the main (or original) problem:
Main Start a psp with the line:
1 {?{M, ∼M}} Main
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Specific rules H
Where {?{M, ∼M}} is the main (or original) problem:
Main Start a psp with the line:
1 {?{M, ∼M}} Main
Target rule (to choose a target that one tries to obtain)
Target If P is the problem of an unmarked problem line, and A is a
direct answer of a member of P, then one may add:
k [A] A Target
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Specific rules H
Where {?{M, ∼M}} is the main (or original) problem:
Main Start a psp with the line:
1 {?{M, ∼M}} Main
Target rule (to choose a target that one tries to obtain)
Target If P is the problem of an unmarked problem line, and A is a
direct answer of a member of P, then one may add:
k [A] A Target
Derive problems:
DP If A is an unmarked target from problem line i
and [B1, . . . , Bn] A is the formula of an unmarked line j,
then one may add:
k {?{B1, ∼B1}, . . . , ?{Bn, ∼Bn}} i, j; DP
3.2 3
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3.3 An example H
main problem: ?{p ∨ q, ∼(p ∨ q)}
premise set: {∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u}
H
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
2 [∼(p ∨ q)] ∼(p ∨ q) Target
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
2 [∼(p ∨ q)] ∼(p ∨ q) Target D3
3 [∼p, ∼q] ∼(p ∨ q) 2; C∼∨E D3
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
2 [∼(p ∨ q)] ∼(p ∨ q) Target D3
3 [∼p, ∼q] ∼(p ∨ q) 2; C∼∨E D3
4 [p ∨ q] p ∨ q Target
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
2 [∼(p ∨ q)] ∼(p ∨ q) Target D3
3 [∼p, ∼q] ∼(p ∨ q) 2; C∼∨E D3
4 [p ∨ q] p ∨ q Target
5 [p] p ∨ q 4; C∨E D5
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
2 [∼(p ∨ q)] ∼(p ∨ q) Target D3
3 [∼p, ∼q] ∼(p ∨ q) 2; C∼∨E D3
4 [p ∨ q] p ∨ q Target
5 [p] p ∨ q 4; C∨E D5
6 [q] p ∨ q 4; C∨E
H
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
pursued answer: q
![Page 45: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/45.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
![Page 46: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/46.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
4 and 6 have no premise in their path
![Page 47: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/47.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
![Page 48: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/48.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E
![Page 49: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/49.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E D12
12 [q, t] q 11; ∨E I12
12: inoperative line
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E D12
12 [q, t] q 11; ∨E I12
13 [u] ∼t ∨ q 10; C∨E
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E D12
12 [q, t] q 11; ∨E I12
13 [u] ∼t ∨ q 10; C∨E
14 [u, t] q 13; ∨E
![Page 52: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/52.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E D12
12 [q, t] q 11; ∨E I12
13 [u] ∼t ∨ q 10; C∨E
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
4 [p ∨ q] p ∨ q Target
6 [q] p ∨ q 4; C∨E
7 {?{q, ∼q}} 4, 6; DP
8 [q] q Target
9 (q ∨ u) ⊃ (∼t ∨ q) Prem
10 [q ∨ u] ∼t ∨ q 9; ⊃E
11 [q] ∼t ∨ q 10; C∨E D12
12 [q, t] q 11; ∨E I12
13 [u] ∼t ∨ q 10; C∨E
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
cleaning up for lack of space
H
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
![Page 55: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/55.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
![Page 56: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/56.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
![Page 57: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/57.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E
![Page 58: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/58.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E
20 {?{s, ∼s}} 16, 19; DP
![Page 59: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/59.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E
20 {?{s, ∼s}} 16, 19; DP
21 [∼s] ∼s Target
![Page 60: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/60.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP
16 [t] t Target
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E S22
20 {?{s, ∼s}} 16, 19; DP R22
21 [∼s] ∼s Target R22
22 ∼s Prem
![Page 61: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/61.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E S23
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP R23
16 [t] t Target R23
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E S22 R23
20 {?{s, ∼s}} 16, 19; DP R22
21 [∼s] ∼s Target R22
22 ∼s Prem
23 t 19, 22; Trans
![Page 62: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/62.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E S23 R24
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP R23
16 [t] t Target R23
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E S22 R23
20 {?{s, ∼s}} 16, 19; DP R22
21 [∼s] ∼s Target R22
22 ∼s Prem
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
![Page 63: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/63.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
8 [q] q Target
. . . . . . . . .
14 [u, t] q 13; ∨E S23 R24
15 {?{u, ∼u}, ?{t, ∼t}} 8, 14; DP R23
16 [t] t Target R23
17 (r ∧ t) ∨ s Prem
18 [∼s] r ∧ t 17; ∨E
19 [∼s] t 18; ∧E S22 R23
20 {?{s, ∼s}} 16, 19; DP R22
21 [∼s] ∼s Target R22
22 ∼s Prem
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
25 {?{u, ∼u}} 8, 24; DP
cleaning up for lack of space
H
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{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
25 {?{u, ∼u}} 8, 24; DP
![Page 65: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/65.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
25 {?{u, ∼u}} 8, 24; DP
26 [u] u Target
![Page 66: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/66.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
25 {?{u, ∼u}} 8, 24; DP
26 [u] u Target
27 t ⊃ u Prem
![Page 67: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/67.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans
25 {?{u, ∼u}} 8, 24; DP
26 [u] u Target
27 t ⊃ u Prem
28 [t] u 27; ⊃E S28
![Page 68: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/68.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans S29
25 {?{u, ∼u}} 8, 24; DP R29
26 [u] u Target R29
27 t ⊃ u Prem
28 [t] u 27; ⊃E S28 R29
29 u 23, 28; Trans
![Page 69: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/69.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main
. . .
6 [q] p ∨ q 4; C∨E S30
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans S29 R30
25 {?{u, ∼u}} 8, 24; DP R29
26 [u] u Target R29
27 t ⊃ u Prem
28 [t] u 27; ⊃E S28 R29
29 u 23, 28; Trans
30 q 24, 29; Trans
![Page 70: 3 Problem-solving processeslogica.ugent.be/dirk//_francq1803.pdf · 3 Problem-solving processes 3.1 Aim and introductory remarks 3.2 Problem-solving processes: first elements 3.3](https://reader035.vdocuments.net/reader035/viewer/2022062604/5fc571afb47bba3c786412ea/html5/thumbnails/70.jpg)
{∼s, ∼u ∨ r, (r ∧ t) ∨ s, (q ∨ u) ⊃ (∼t ∨ q), t ⊃ u} H
1 {?{p ∨ q, ∼(p ∨ q)}} Main R31
. . .
6 [q] p ∨ q 4; C∨E S30 R31
. . .
23 t 19, 22; Trans
24 [u] q 14, 23; Trans S29 R30
25 {?{u, ∼u}} 8, 24; DP R29
26 [u] u Target R29
27 t ⊃ u Prem
28 [t] u 27; ⊃E S28 R29
29 u 23, 28; Trans
30 q 24, 29; Trans
31 p ∨ q 6, 30; Trans
3.3 3
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3.4 The rules and the permissions and obligations H
Prem, FAR, CAR, EM, EM0, Trans, Main, Target, DP
permissions + further comments on some rules
(marking definitions follow)
H
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H
Main Start a psp with the line:
1 {?{M, ∼M}} Main
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H
Main Start a psp with the line:
1 {?{M, ∼M}} Main
Target If P is the problem of an unmarked problem line,
and A is a direct answer of a member of P,
then one may add:
k [A] A Target
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H
Main Start a psp with the line:
1 {?{M, ∼M}} Main
Target If P is the problem of an unmarked problem line,
and A is a direct answer of a member of P,
then one may add:
k [A] A Target
Prem If A is an unmarked target, B ∈ Γ, and pp(A, B),
then one may add:
k B Prem
H
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Formula analysing rules (bring one closer to a target):
[∆] a[∆] a1 [∆] a2
[∆] b[∆ ∪ {∗b2}] b1 [∆ ∪ {∗b1}] b2
FAR If C is an unmarked target,
[∆] A is the formula of an unmarked line i,
[∆] A / [∆ ∪ ∆′] B is a formula analysing rule,
and pp(C, B),
then one may add:
k [∆ ∪ ∆′] B i; R
in which R is the name of the formula analysing rule.
H
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Condition analysing rules (reveal other means to reach a target):
[∆ ∪ {a}] A[∆ ∪ {a1, a2}] A
[∆ ∪ {b}] A[∆ ∪ {b1}] A [∆ ∪ {b2}] A
CAR If A is an unmarked target,
[∆ ∪ {B}] A is the formula of an unmarked line i,
and [∆ ∪ {B}] A / [∆ ∪ ∆′] A is a condition analysing rule,
then one may add:
k [∆ ∪ ∆′] A i; R
in which R is the name of the condition analysing rule.
H
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Eliminate some problems without answering them:
EM0 If [∆ ∪ {∗A}] A is the formula of a line i that is neither
R-marked nor I-marked, then one may add:
k [∆] A i; EM0
EM If A is an unmarked target,
[∆ ∪ {B}] A and [∆′ ∪ {∼B}] A are the respective formulas of
the unmarked or only D-marked lines i and j,
and ∆ ⊆ ∆′ or ∆′ ⊆ ∆,
then one may add:
k [∆ ∪ ∆′] A i, j; EM
H
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eliminate obtained elements from a condition (and solved questions
from a problem)
and
summarize remaining problems (and paths):
Trans If A is an unmarked target,
and [∆ ∪ {B}] A and [∆′] B are the respective formulas of the
at most S-marked (not R-, I- or D-marked) lines i and j,
then one may add:
k [∆ ∪ ∆′] A i, j; Trans
H
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handle derived problems:
DP If A is an unmarked target from problem line i
and [B1, . . . , Bn] A is the formula of an unmarked line j,
then one may add:
k {?{B1, ∼B1}, . . . , ?{Bn, ∼Bn}} i, j; DP
H
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no instruction for applying EFQ
in view of the intended applications
(deriving predictions, finding explanations, etc.)
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no instruction for applying EFQ
in view of the intended applications
(deriving predictions, finding explanations, etc.)
the only exception seems to be: answering {?{Γ `CL A, Γ 0CL A}}
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no instruction for applying EFQ
in view of the intended applications
(deriving predictions, finding explanations, etc.)
the only exception seems to be: answering {?{Γ `CL A, Γ 0CL A}}
but every possible application seems to require CL−.
H
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Marking definitions
redundant lines are R-marked: (unconditional A identified with [∅] A)
Definition 1 An at most S-marked declarative line i that has [∆] A as
its formula is R-marked at a stage iff, at that stage, [Θ] A is the formula
of a line for some Θ ⊂ ∆.
Definition 2 An unmarked problem line i is R-marked at a stage iff, at
that stage, a direct answer A of a question of line i is the formula of a
line.
H
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the following definitions require:
· target from a problem line
· resolution line
· direct target from
· target sequence
· grounded target sequence
H
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inoperative lines are I-marked (not useful for extant problem):
Definition 3 An at most S-marked target line that has [A] A as its
formula is I-marked at a stage iff every problem line from which A is a
target is marked at that stage.
Definition 4 An at most S-marked resolution line of which [∆1] A1 is
the formula for some ∆1 6= ∅ is I-marked at a stage iff, at that stage,
for every grounded target sequence 〈[∆n] An, . . . , [∆1] A1〉,
(i) some target [Ai] Ai (1 ≤ i ≤ n) is marked, or
(ii) {An, . . . , A1} ∩ ∆1 6= ∅, or
(iii) ∆1 ∪ . . . ∪ ∆n ∪ Γ◦s is flatly inconsistent.
Definition 5 An unmarked problem line is I-marked iff no unmarked
resolution line generates it.
H
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Dead end lines are D-marked (no further action from such line)
· A is a dead end (A is literal and not a positive part of a premise)
· CAR-descendant of [∆ ∪ {A}] B
Definition 6 An at most S-marked resolution line with formula [∆] A is
D-marked at a stage iff some B ∈ ∆ is a dead end or, at that stage, all
CAR-descendants of [∆] A occur in the psp and are D-marked.
Definition 7 An at most S-marked target line with formula [A] A is
D-marked at a stage iff A is a dead end or no further action can be
taken in view of target A.
H
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it can be shown that, for all consistent Γ: H
(i) the procedure applied to Γ and {?{A, ∼A}} results in the answer A,
iff Γ `CL A
and
(ii) the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A iff Γ 0CL A
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it can be shown that, for all consistent Γ: H
(i) the procedure applied to Γ and {?{A, ∼A}} results in the answer A,
iff Γ `CL A
and
(ii) the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A iff Γ 0CL A
for the predicative case:
if the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A, then Γ 0CL A
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it can be shown that, for all consistent Γ: H
(i) the procedure applied to Γ and {?{A, ∼A}} results in the answer A,
iff Γ `CL A
and
(ii) the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A iff Γ 0CL A
for the predicative case:
if the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A, then Γ 0CL A
because
(ii′) the procedure applied to Γ and {?{A, ∼A}} stops without the main
problem being answered, or results in the answer ∼A, or does not stop
iff Γ 0CL A
H
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Speed up the procedure by S-marks
· Γ◦s: union of Γ and of the set of conditionless formulas
that occur at stage s of the psp
Definition 8 A R-unmarked resolution line in which [∆1] A1 is derived is
S-marked iff
(i) ∆1 ∩ Γ◦s 6= ∅, or
(ii) for some target sequence 〈[∆n] An, . . . , [∆1] A1〉, {An} ∪ ∆1 is
flatly inconsistent whereas ∆1 is not flatly inconsistent, or
(iii) ∆1 ⊂ ∆n ∪ . . . ∪ ∆2 for some target sequence
〈[∆n] An, . . . , [∆1] A1〉.
3.4 3
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3.5 Answerable questions H
A is a set of questions that can be answered by standard means
(for example: observation or experiment)
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3.5 Answerable questions H
A is a set of questions that can be answered by standard means
(for example: observation or experiment)
idea: whenever an unmarked target is a positive part of a direct answer
of a member of A, that question can be answered (outside the proof)
and the answer can be introduced as a new premise
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3.5 Answerable questions H
A is a set of questions that can be answered by standard means
(for example: observation or experiment)
idea: whenever an unmarked target is a positive part of a direct answer
of a member of A, that question can be answered (outside the proof)
and the answer can be introduced as a new premise
whether some ?{A, ∼A} ∈ A is launched depends on pragmatic
(economic) considerations
H
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
a target A justifies asking the answerable question
· ?{A, ∼A}
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
a target A justifies asking the answerable question
· ?{A, ∼A}· ?{A ∧ B, ∼A ∧ B}
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
a target A justifies asking the answerable question
· ?{A, ∼A}· ?{A ∧ B, ∼A ∧ B}· ?{A ∨ B, ∼A ∨ B}
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
a target A justifies asking the answerable question
· ?{A, ∼A}· ?{A ∧ B, ∼A ∧ B}· ?{A ∨ B, ∼A ∨ B}· ?{B ⊃ A, ∼(B ⊃ A)}etc.
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H
“dead end” needs to be redefined: A is a dead end iff it is not a
positive part of a premise or of a direct answer to a member of A.
a target A justifies asking the answerable question
· ?{A, ∼A}· ?{A ∧ B, ∼A ∧ B}· ?{A ∨ B, ∼A ∨ B}· ?{B ⊃ A, ∼(B ⊃ A)}etc.
so A need not be an unmarked target in order for ?{A, ∼A} to be
launched
H
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H
a launched question is answered outside the psp
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H
a launched question is answered outside the psp
its answer is introduced as a new premise
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H
a launched question is answered outside the psp
its answer is introduced as a new premise
this is awkward from a logical point of view
so better
redefine A as a set of couples 〈?{A, ∼A}, B〉 with B ∈ {A, ∼A}
B is determined but unknown to the problem solver
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H
a launched question is answered outside the psp
its answer is introduced as a new premise
this is awkward from a logical point of view
so better
redefine A as a set of couples 〈?{A, ∼A}, B〉 with B ∈ {A, ∼A}
B is determined but unknown to the problem solver
that A is the target justifies launching 〈?{A, ∼A}, A〉 just as much as it
justifies launching 〈?{A, ∼A}, ∼A〉 (etc.)
H
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H
instruction:
New If A is the target of the unmarked target line i, pp(A, B) or
pp(A, ∼B), and 〈?{B, ∼B}, C〉 ∈ A (where C ∈ {B, ∼B}),then one may add:
k C i; New
obvious from New:
which member of A was launched in view of which target
H
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Γ = {(q ∧ r) ⊃ p, ∼s ∨ q, s, . . .} A = {〈?{q ⊃ r, ∼(q ⊃ r)}, q ⊃ r〉, . . .}.
1 {?{p, ∼p}} Main R19
2 [p] p Target R19
3 (q ∧ r) ⊃ p Prem
4 [q ∧ r] p 3; ⊃E R19
5 [q, r] p 4; C∧E S9 R10
6 {?{q, ∼q}, ?{r, ∼r}} 2, 5; DP I10
7 [r] r Target I10
8 q ⊃ r 7; New
9 [q] r 8; C⊃E I10
10 [q] p 5, 9; Trans R19
11 {?{q, ∼q}} 2, 10; DP R18
12 [q] q Target R18
13 ∼s ∨ q Prem
14 [s] q 13; ∨E S17 R18
15 {?{s, ∼s}} 12, 14; DP R17
16 [s] s Target R17
17 s Prem
18 q 14, 17; Trans
19 p 10, 18; Trans3.5 3
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3.6 Variants, extensions and comments
• procedural variants
• extensions to other logics
including adaptive logics to handle inconsistencies, abduction,
inductive generalization, . . . (fifth lecture)
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3.6 Variants, extensions and comments
• procedural variants
• extensions to other logics
including adaptive logics to handle inconsistencies, abduction,
inductive generalization, . . . (fifth lecture)
procedure was not intended to be maximally efficient in view of its aim:
(i) explicate actual problem-solving processes
(ii) avoid steps that are useless with respect to the main problem, the
premises and the directly answerable questions
(iii) easily generalizable to other logics (devise prospective dynamics)
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3.6 Variants, extensions and comments
• procedural variants
• extensions to other logics
including adaptive logics to handle inconsistencies, abduction,
inductive generalization, . . . (fifth lecture)
procedure was not intended to be maximally efficient in view of its aim:
(i) explicate actual problem-solving processes
(ii) avoid steps that are useless with respect to the main problem, the
premises and the directly answerable questions
(iii) easily generalizable to other logics (devise prospective dynamics)
procedure is probably not maximally efficient in its kind
· this requires further research
· it does not undermine the main aim of the enterprise:
to delineate sensible reasoning
3.6 3