## Review of K Propositional Rules

**There are the ordinary (non-modal) tree propositional rules plus **

**The Modal Negation (MN) rules**

The Reading a Counter Example from a Tree Widget
martin
Sat, 01/04/2014 - 21:34
## Exercise: Finding a counter-example.

Topic

Logical System

Help with Reading a Counter Example [Generic]
martin
Sun, 03/31/2013 - 13:50
### Reading a counter example from an open branch

Topic

2013

*[This is a Quicktime Movie, click the Play button to view it. The logical symbols you see in use may be different to the ones you are familiar with (sorry about that, but it is not practical to produce different movies for all the minor variations in symbols). Any differences will not affect the principles being explained here.] *

Your browser does not support html5 video.

The Tree Widget
martin
Fri, 03/01/2013 - 20:04
### An example of the tree widget in use (and we are showing a different parser here to the earlier ones)

Topic

2013

The logical symbols in use are ¬ ∧ ∨ → ↔ ∀ ∃ .

Determine whether these arguments are valid (ie try to produce closed trees for them)

a) ∀x(F(x)→G(x)), ∃x¬G(x) ∴ ∃x¬F(x)

b) ∀x(F(x)→∀yG(y)), F(a) ∴ ∀xG(x)

c) ∀x(A(x)→B(x)), ∀x(¬A(x)→C(x))∴ ∀x(¬B(x)→¬C(x))

d) ∃xF(x),∀x(¬G(x)→¬F(x)),∀xM(x) ∴ ∃xG(x)∧∃xM(x)

Reading a Counter Example from the Tree
martin
Wed, 06/20/2012 - 22:29

Topic

Logical System

Logical System

**There are the ordinary (non-modal) tree propositional rules plus **

**The Modal Negation (MN) rules**

Logical System

Review of Tree Propositional Rules
martin
Sat, 06/02/2012 - 16:35

Topic

Logical System

6/2/12
##
Review of Tree Propositional Rules, shown as patterns

Here the letters 'P' and 'Q' are being used to stand for entire well formed formulas (so, on a particular occasion, 'P' might stand for the atomic formula 'F' and, on another occasion, it might stand for the compound formula 'F&G').

Tree Predicate Exercises: Roll your own
martin
Sat, 06/02/2012 - 11:40

Topic

Logical System

Review of Tree Predicate Rules
martin
Sat, 06/02/2012 - 11:39

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∃D. The constant, a, must be new to the branch [here the computer will choose for you]

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∀D. Any closed term, stage 1, your choice

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∀D. Any closed term, stage 2, the constant 'a' chosen

Topic

Logical System

Set Theory (and Russell's Paradox)
martin
Thu, 05/31/2012 - 14:55

Topic

Logical System