Question 1096564
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||x|-|u|-|y-v|| <= |x-y| + |u-v|

Sorry, that's not always true because

Let x=2, u=4, y=3, v=5   

{{{abs(abs(x)^""-abs(u)-abs(y-v))<=abs(x-y)+abs(u-v)}}}

{{{abs(abs(2)^""-abs(4)-abs(3-5))<=abs(2-3)+abs(4-5)}}}

{{{abs(2^""-4-abs(-2))<=abs(-1)+abs(-1)}}}

{{{abs(2^""-4-2)<=1+1}}}

{{{abs(-4)<=2}}}

{{{4<=2}}}

That's false!

Maybe you copied it wrong.  If so, 
copy it correctly in the thank-you 
note form below and I'll get back 
to you by email.

Edwin</pre></b></font>