Theories very close to PA where Kreisel's conjecture is false

被引:2
|
作者
Hrubes, Pavel [1 ]
机构
[1] Acad Sci Czech Republ, Inst Math, CR-11567 Prague, Czech Republic
关键词
D O I
10.2178/jsl/1174668388
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We give four examples of theories in which Kreisel's Conjecture is false: (1) the theory PA(-) obtained by adding a function symbol minus, '-', to the language of PA, and the axiom for all x for all y for all z (x - y = z) equivalent to (x = y + z boolean OR(x < y boolean AND z 0)); (2) the theory-E of integers; (3) the theory PA (q) obtained by adding a function symbol q (of arity >= 1) to PA, assuming nothing about q; (4) the theory PA (N) containing a unary predicate N(x) meaning 'x is a natural number'. In Section 6 we suggest a counterexample to the so called Sharpened Kreisel's Conjecture.
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页码:123 / 137
页数:15
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