Commuting Conversions vs. the Standard Conversions of the “Good” Connectives
Commuting Conversions vs. the Standard Conversions of the “Good” Connectives
复制标题
通勤转换与“好”连接词的标准转换
DOI:
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发表时间:
2009
期刊:
影响因子:
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通讯作者:
Gilda Ferreira
中科院分区:
文献类型:
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作者:
Fernando Ferreira;Gilda Ferreira
Commuting conversions were introduced in the natural deduction calculus as ad hoc devices for the purpose of guaranteeing the subformula property in normal proofs. In a well known book, Jean-Yves Girard commented harshly on these conversions, saying that ‘one tends to think that natural deduction should be modified to correct such atrocities.’ We present an embedding of the intuitionistic predicate calculus into a second-order predicative system for which there is no need for commuting conversions. Furthermore, we show that the redex and the conversum of a commuting conversion of the original calculus translate into equivalent derivations by means of a series of bidirectional applications of standard conversions.