Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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## #1 2013-05-02 15:06:22

Agnishom
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### Dots and Lines

If G is a regular graph and d, e and v denote the degree, the number of edges and the number of vertices respectively, then e = dv/2.

Prove the above statement

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'Who are you to judge everything?' -Alokananda

## #2 2013-05-14 13:39:44

John E. Franklin
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### Re: Dots and Lines

since a line segment or "edge" has two ends, then yes, 1/2 is the formula.  v=dots  d=ends of lines on a dot.   e=#ofline segs
Pretty obvious really if you draw a few.  but to prove it, ask Ricky.

igloo myrtilles fourmis

## #3 2013-05-19 00:55:36

Agnishom
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### Re: Dots and Lines

Ricky? He's gone

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'Who are you to judge everything?' -Alokananda