Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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Topic review (newest first)

kylekatarn
2005-08-31 09:08:03

omg I can't remember that from my philosophy classes=P

You can always try a Venn Diagram approach.

yagmai
2005-08-30 22:18:34

hi guys,
can help me to check if my premises are correct?? how do u prove it?thanks alot

1) Every1 shouts or cries. not every1 cries. hence , some pple shout and dun cry.
is this correct?
S(x): x shouts
C(x): x cries

∀x(S(x) -> C(x))
∃x(~C(x))

thus. ∃x(S(x) ^ ~C(x))

2) All problems are difficult and frustrating. some problems are challenging. therefore some problems are challenging and frustrating.

D(x): x is difficult
F(x): x is frustrating
P(x): x is problem
C(x): x is challenging

how shld i approach this qns?
∀x(P(x) -> D(x) ^ F(x))
∃x(P(x) ^ C(x))
thus ∃x(C(x) ^ F(x))

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