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But lets bring this back to a more real example. A user wanting to
express some computations that have some dependencies, would write out
their computations in some order, expecting their order to be preserved
because of the dependencies. If you only support single assignment on
variables (e.g. the data), then an example like the one below could
never deadlock because the single assignment would be violated on the
2nd statement. Perhaps things are more complicated if you support
multiple assignments per variables, but that is not the case for Swift,
right? <br>
<br>
I am trying to understand if this deadlock is happening in Swift due to
some particular implementation detail in Swift (or underlying pieces),
or is it a fundamental flaw in the DAG based approach with single
assignment variables? Or is it due to something completely different?<br>
<br>
Thanks,<br>
Ioan<br>
<pre class="moz-signature" cols="72">--
=================================================================
Ioan Raicu, Ph.D.
NSF/CRA Computing Innovation Fellow
=================================================================
Center for Ultra-scale Computing and Information Security (CUCIS)
Department of Electrical Engineering and Computer Science
Northwestern University
2145 Sheridan Rd, Tech M384
Evanston, IL 60208-3118
=================================================================
Cel: 1-847-722-0876
Tel: 1-847-491-8163
Email: <a class="moz-txt-link-abbreviated" href="mailto:iraicu@eecs.northwestern.edu">iraicu@eecs.northwestern.edu</a>
Web: <a class="moz-txt-link-freetext" href="http://www.eecs.northwestern.edu/~iraicu/">http://www.eecs.northwestern.edu/~iraicu/</a>
<a class="moz-txt-link-freetext" href="https://wiki.cucis.eecs.northwestern.edu/">https://wiki.cucis.eecs.northwestern.edu/</a>
=================================================================
=================================================================
</pre>
<br>
<br>
Ben Clifford wrote:
<blockquote
cite="mid:Pine.LNX.4.64.1002191650290.15193@dildano.hawaga.org.uk"
type="cite">
<blockquote type="cite">
<pre wrap="">Mathematically, the two different sequences evaluate to different values:
x = y + 1
y = x + 1
assuming y = 0, x = 1
</pre>
</blockquote>
<pre wrap=""><!---->
I mean in simultaneous equations (linear algebra) - in other words, "find
(through whatever means you care to use) a value of x and y such that the
above two equations are both satisfied" - there is no value of x and y
that satisfies that.
</pre>
</blockquote>
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