#216:Formal Logic

Season:	1
Number:	216
Wave:	2
Color:	black
Suit:	maze
Corner:	bottom right
Card's Points:	54
Card Group's Points:	216
Reverse:	map
Playing Card:
Number Marks:
Official Statistics

Key
/'∀/' Corresponds roughly to the English word /'every/'.
'∃' Corresponds roughly to the English word /'some/'.
The variables x,y,z range over objects.
/'_→_/' Corresponds roughly to the English phrase /'if_then_/'.

Question 1
Which of the following formalises the claim that every person has a common ancestor (where /'P/' = /'_is a person/' and /'A/' = /'is an ancestor of __/').

(i) (∃x)(∀y)(P(y)→A(xy))
(ii) (∀x)(∃y)(P(x)→A(yx))
(iii) (∀x)(P(x)→A(xx))

Question 2
What is the name of the paradox that is represented in the following set-theorectic notation.

R = {x : x ∉ x}

(i) Sorities Paradox
(ii) Cantor's Paradox
(iii) Russell's Paradox 'A'='is an ancestor of_ _' should be 'A'='_ is an ancestor of _'

The River Mazy Part 1

Perplex City was originally founded
south of the River Mazy, which has
influenced the city\'s character
throughout its history. The river\'s
course has been changed many times
over the centuries and flood barriers
have been installed further upstream.
Frequent ferry services operate
regularly across and along the river.

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