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→Theory of parsing expression grammars: Undecidability of language emptiness. |
→Practical significance: Typo |
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<syntaxhighlight lang="peg">
Sum ← Term ( '+' Term / '-' Term )*
Args
</syntaxhighlight>
A difference lies in the [[abstract syntax tree]]s generated: with recursion each <code>Sum</code> or <code>Args</code> can have at most two children, but with repetition there can be arbitrarily many. If later stages of processing require that such lists of children are recast as trees with bounded [[degree (graph theory)|degree]], for example microprocessor instructions for addition typically only allow two operands, then properties such as [[left-associative|left-associativity]] would be imposed after the PEG-directed parsing stage.
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