| 释义 |
non-conˈjunction
[non- 1.]
1. Cytology. The failure of homologous chromosomes to pair at meiosis. rare.
1925J. Belling in Jrnl. Genetics XV. 256 Non-conjunction. This term is used instead of non-conjugation, because in most cases it cannot be told whether conjugation, that is, parasynapsis, has taken place or not, with regard to the chromosome pair in question... Non-conjunction cannot be distinguished from true non-disjunction, in the later stages.
2. Logic. The relation of the terms in a proposition asserting the negative of a conjunctive proposition (‘not both..and..’).
1926H. M. Sheffer in Isis VIII. 229 The authors consider one of the cardinal improvements in the new edition to consist in their substitution, for the two operations of propositional negation and disjunction, of the single operation of non-conjunction. 1956A. Church Introd. Math. Logic (rev. ed.) I. ii. 134 Sheffer uses the sign of disjunction, {logicor}, inverted as a sign of non-disjunction; he introduces non-conjunction only in a footnote and uses no special sign for it. Ibid. 135 Taking non-conjunction as the only primitive connective, give definitions of the singulary and remaining binary connectives. 1957Encycl. Brit. XIV. 306/1 We shall use..the sign {vb} to denote non-conjunction (‘p{vb}q’ to mean ‘not both p and q’). Ibid., If the sign of non-conjunction (Sheffer's stroke) is taken as primitive, all the other connectives can be defined from this one. 1965Hughes & Londey Elem. Formal Logic viii. 54 The following are valid: (i) (p {expon} q) ≡ ∼ (p.q), (ii) (p{decr} q) ≡ ∼ (p {logicor} q), which suggests the names ‘non-conjunction’ and ‘non-disjunction’ for ‘{expon}’ and ‘{decr}’ respectively. |