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McCabe's characterization of the [[forbidden graph]]s for structured programming can be considered incomplete, at least if the Dijkstra's D structures are considered the building blocks.<ref>{{cite journal | doi = 10.1093/comjnl/26.3.270 | title=Flowchart Schemata and the Problem of Nomenclature | journal=The Computer Journal | date=1983 | volume=26 | issue=3 | pages=270–276 | first=M. H. | last=Williams| doi-access=free }}</ref>{{rp|274–275}}{{clarify|date=July 2014}}
Up to 1990 there were quite a few proposed methods for eliminating gotos from existing programs, while preserving most of their structure. The various approaches to this problem also proposed several notions of equivalence, which are stricter than simply Turing equivalence, in order to avoid output like the folk theorem discussed above. The strictness of the chosen notion of equivalence dictates the minimal set of control flow structures needed. The 1988 [[JACM]] paper by Lyle Ramshaw surveys the field up to that point, as well proposing its own method.<ref>{{Cite journal | doi = 10.1145/48014.48021| title = Eliminating go to's while preserving program structure| journal = Journal of the ACM| volume = 35| issue = 4| pages = 893–920| year = 1988| last1 = Ramshaw | first1 = L. | s2cid = 31001665| doi-access = free}}</ref> Ramshaw's algorithm was used for example in some Java [[decompiler]]s because the [[Java virtual machine]] code has branch instructions with targets expressed as offsets, but the high-level Java language only has multi-level <code>break</code> and <code>continue</code> statements.<ref name="Nolan2004">{{cite book|author=Godfrey Nolan|title=Decompiling Java|year=2004|publisher=Apress|isbn=978-1-4302-0739-9|page=142}}</ref><ref>https://www.usenix.org/legacy/publications/library/proceedings/coots97/full_papers/proebsting2/proebsting2.pdf {{Bare URL PDF|date=March 2022}}</ref><ref>http://www.openjit.org/publications/pro1999-06/decompiler-pro-199906.pdf {{Bare URL PDF|date=March 2022}}</ref> Ammarguellat (1992) proposed a transformation method that goes back to enforcing single-exit.<ref name="amma92">{{cite journal | doi = 10.1109/32.126773 | title=A control-flow normalization algorithm and its complexity | journal=IEEE Transactions on Software Engineering | date=1992 | volume=18 | issue=3 | pages=237–251 | first=Z. | last=Ammarguellat}}</ref>
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