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== Implications and refinements ==
The Böhm–Jacopini proof did not settle the question of whether to adopt [[structured programming]] for software development, partly because the construction was more likely to obscure a program than to improve it. On the contrary, it signalled the beginning of the debate. [[Edsger Dijkstra]]'s famous letter, "'''[[Considered Harmful|Go To Statement Considered Harmful]]'''<!--boldface per WP:R#PLA-->," followed in 1968.<ref>{{cite journal|last=Dijkstra|first=Edsger|author-link=Edsger W. Dijkstra|year=1968|title=Go To Statement Considered Harmful|journal=Communications of the ACM|volume=11|issue=3|pages=147–148|doi=10.1145/362929.362947|s2cid=17469809 |url=http://www.acm.org/classics/oct95/|url-status=dead|archive-url=https://web.archive.org/web/20070703050443/http://www.acm.org/classics/oct95/|archive-date=2007-07-03}}</ref>
Some academics took a purist approach to the Böhm–Jacopini result and argued that even instructions like <code>break</code> and <code>return</code> from the middle of loops are bad practice as they are not needed in the Böhm–Jacopini proof, and thus they advocated that all loops should have a single exit point. This purist approach is embodied in the [[Pascal (programming language)|Pascal programming language]] (designed in 1968–1969), which up to the mid-1990s was the preferred tool for teaching introductory programming classes in academia.<ref name="roberts">Roberts, E. [1995] "[http://cs.stanford.edu/people/eroberts/papers/SIGCSE-1995/LoopExits.pdf Loop Exits and Structured Programming: Reopening the Debate]," ACM SIGCSE Bulletin, (27)1: 268–272.</ref>
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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}}</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>
==Application to Cobol==
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