**Next message:**Victor Luchangco: "Re: JavaMemoryModel: Examples similar to tests 5 and 10"**Previous message:**Sylvia Else: "Re: JavaMemoryModel: Examples similar to tests 5 and 10"**In reply to:**Sylvia Else: "Re: JavaMemoryModel: Examples similar to tests 5 and 10"**Next in thread:**Victor Luchangco: "Re: JavaMemoryModel: Examples similar to tests 5 and 10"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

*>
*

*> So a value is out of thin air in M/P
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*> only if there
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*> exists a proof that a write of the value did not occur.
*

Note that the write of the value that is read (i.e., 1) does occur. It is

the write of 2 that occurs in one example and doesn't in another. But in

both examples, in the actual execution, nobody reads the value 2. So why

should it matter whether the write of 2 occurs or not.

*> BTW, in the quoted code below, I've changed T4, which seemed
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*> to have been
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*> garbled in transmission (at least in the version I received). Perhaps
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*> Sarita could confirm that I've correctly stated it.
*

Yes, it is correctly stated.

Sarita

*>
*

*> Sylvia.
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*>
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*> >Example 1: Initially all variables are 0
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*> >
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*> >T1
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*> >r1=X
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*> >if (r1==1)
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*> > Z=1
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*> >
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*> >T2
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*> >r2=Z
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*> >if (r2==1 || r2==2)
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*> > X=1
*

*> >
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*> >T3
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*> >Z=2
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*> >
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*> >Result: r1=r2=1
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*> >
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*> >
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*> >Example 2: Initially all variables are 0
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*> >
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*> >T1
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*> >r1=X
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*> >if (r1==1)
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*> > Z=1
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*> >
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*> >T2
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*> >r2=Z
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*> >if (r2==1 || r2==2)
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*> > X=1
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*> >
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*> >T3
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*> >Y = 1
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*> >
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*> >T4
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*> >r4 = Y
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*> >if (r4 == 1)
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*> > Z = 2
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*> >
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*> >Result: r1=r2=1, r4 = 0
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*>
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*> -------------------------------
*

*> JavaMemoryModel mailing list -
*

*> http://www.cs.umd.edu/~pugh/java/memoryModel
*

*>
*

-------------------------------

JavaMemoryModel mailing list - http://www.cs.umd.edu/~pugh/java/memoryModel

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