注入集合和射出集

Pub Date : 2024-09-16 DOI:10.1002/malq.202300059
Natthajak Kamkru, Nattapon Sonpanow
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Among our results, we show that “<span></span><math>\n <semantics>\n <mrow>\n <msup>\n <mo>seq</mo>\n <mrow>\n <mn>1</mn>\n <mo>−</mo>\n <mn>1</mn>\n </mrow>\n </msup>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n <mo>≠</mo>\n <mi>I</mi>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n <mo>≠</mo>\n <mo>seq</mo>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n </mrow>\n <annotation>$\\operatorname{seq}^{1-1}(\\mathfrak {m})\\ne I(\\mathfrak {m})\\ne \\operatorname{seq}(\\mathfrak {m})$</annotation>\n </semantics></math>”, “<span></span><math>\n <semantics>\n <mrow>\n <msup>\n <mo>seq</mo>\n <mrow>\n <mn>1</mn>\n <mo>−</mo>\n <mn>1</mn>\n </mrow>\n </msup>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n <mo>≠</mo>\n <mi>J</mi>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n <mo>≠</mo>\n <mo>seq</mo>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n </mrow>\n <annotation>$\\operatorname{seq}^{1-1}(\\mathfrak {m})\\ne J(\\mathfrak {m})\\ne \\operatorname{seq}(\\mathfrak {m})$</annotation>\n </semantics></math>” and “<span></span><math>\n <semantics>\n <mrow>\n <msup>\n <mo>seq</mo>\n <mrow>\n <mn>1</mn>\n <mo>−</mo>\n <mn>1</mn>\n </mrow>\n </msup>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n <mo>&lt;</mo>\n <msup>\n <mi>m</mi>\n <mi>m</mi>\n </msup>\n <mo>≠</mo>\n <mo>seq</mo>\n <mrow>\n <mo>(</mo>\n <mi>m</mi>\n <mo>)</mo>\n </mrow>\n </mrow>\n <annotation>$\\operatorname{seq}^{1-1}(\\mathfrak {m})&amp;lt;\\mathfrak {m}^\\mathfrak {m}\\ne \\operatorname{seq}(\\mathfrak {m})$</annotation>\n </semantics></math>” are provable for an arbitrary infinite cardinal <span></span><math>\n <semantics>\n <mi>m</mi>\n <annotation>$\\mathfrak {m}$</annotation>\n </semantics></math>, and these are the best possible results, in the Zermelo-Fraenkel set theory (<span></span><math>\n <semantics>\n <mi>ZF</mi>\n <annotation>$\\mathsf {ZF}$</annotation>\n </semantics></math>) without the Axiom of Choice. 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Among our results, we show that “<span></span><math>\\n <semantics>\\n <mrow>\\n <msup>\\n <mo>seq</mo>\\n <mrow>\\n <mn>1</mn>\\n <mo>−</mo>\\n <mn>1</mn>\\n </mrow>\\n </msup>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n <mo>≠</mo>\\n <mi>I</mi>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n <mo>≠</mo>\\n <mo>seq</mo>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n <annotation>$\\\\operatorname{seq}^{1-1}(\\\\mathfrak {m})\\\\ne I(\\\\mathfrak {m})\\\\ne \\\\operatorname{seq}(\\\\mathfrak {m})$</annotation>\\n </semantics></math>”, “<span></span><math>\\n <semantics>\\n <mrow>\\n <msup>\\n <mo>seq</mo>\\n <mrow>\\n <mn>1</mn>\\n <mo>−</mo>\\n <mn>1</mn>\\n </mrow>\\n </msup>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n <mo>≠</mo>\\n <mi>J</mi>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n <mo>≠</mo>\\n <mo>seq</mo>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n <annotation>$\\\\operatorname{seq}^{1-1}(\\\\mathfrak {m})\\\\ne J(\\\\mathfrak {m})\\\\ne \\\\operatorname{seq}(\\\\mathfrak {m})$</annotation>\\n </semantics></math>” and “<span></span><math>\\n <semantics>\\n <mrow>\\n <msup>\\n <mo>seq</mo>\\n <mrow>\\n <mn>1</mn>\\n <mo>−</mo>\\n <mn>1</mn>\\n </mrow>\\n </msup>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n <mo>&lt;</mo>\\n <msup>\\n <mi>m</mi>\\n <mi>m</mi>\\n </msup>\\n <mo>≠</mo>\\n <mo>seq</mo>\\n <mrow>\\n <mo>(</mo>\\n <mi>m</mi>\\n <mo>)</mo>\\n </mrow>\\n </mrow>\\n <annotation>$\\\\operatorname{seq}^{1-1}(\\\\mathfrak {m})&amp;lt;\\\\mathfrak {m}^\\\\mathfrak {m}\\\\ne \\\\operatorname{seq}(\\\\mathfrak {m})$</annotation>\\n </semantics></math>” are provable for an arbitrary infinite cardinal <span></span><math>\\n <semantics>\\n <mi>m</mi>\\n <annotation>$\\\\mathfrak {m}$</annotation>\\n </semantics></math>, and these are the best possible results, in the Zermelo-Fraenkel set theory (<span></span><math>\\n <semantics>\\n <mi>ZF</mi>\\n <annotation>$\\\\mathsf {ZF}$</annotation>\\n </semantics></math>) without the Axiom of Choice. 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引用次数: 0

摘要

在本文中,我们研究了注入集合、射出集合和一个集合上所有函数的集合的心数之间的关系,这些集合的心数为 m $\mathfrak {m}$,分别用 I ( m ) $I(\mathfrak {m})$、J ( m ) $J(\mathfrak {m})$和 m m $\mathfrak {m}^\mathfrak {m}$表示。Among our results, we show that “ seq 1 − 1 ( m ) ≠ I ( m ) ≠ seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})\ne I(\mathfrak {m})\ne \operatorname{seq}(\mathfrak {m})$ ”, “ seq 1 − 1 ( m ) ≠ J ( m ) ≠ seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})\ne J(\mathfrak {m})\ne \operatorname{seq}(\mathfrak {m})$ ” and “ seq 1 − 1 ( m ) < m m ≠ seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})&lt;\mathfrak {m}^\mathfrak {m}\ne \operatorname{seq}(\mathfrak {m})$ ” are provable for an arbitrary infinite cardinal m $\mathfrak {m}$ , and these are the best possible results, in the Zermelo-Fraenkel set theory ( ZF $\mathsf {ZF}$ ) without the Axiom of Choice.另外,我们还证明,存在一个无限红心 m $\mathfrak {m}$,使得 S ( m ) = I ( m ) <; J ( m ) $S(\mathfrak {m})=I(\mathfrak {m})&lt;J(\mathfrak {m})$ 其中 S ( m ) $S(\mathfrak {m})$表示一个集合上双射集合的万有性,这个集合的万有性为 m $\mathfrak {m}$ 。
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The set of injections and the set of surjections on a set

In this paper, we investigate the relationships between the cardinalities of the set of injections, the set of surjections, and the set of all functions on a set which is of cardinality m $\mathfrak {m}$ , denoted by I ( m ) $I(\mathfrak {m})$ , J ( m ) $J(\mathfrak {m})$ and m m $\mathfrak {m}^\mathfrak {m}$ , respectively. Among our results, we show that “ seq 1 1 ( m ) I ( m ) seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})\ne I(\mathfrak {m})\ne \operatorname{seq}(\mathfrak {m})$ ”, “ seq 1 1 ( m ) J ( m ) seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})\ne J(\mathfrak {m})\ne \operatorname{seq}(\mathfrak {m})$ ” and “ seq 1 1 ( m ) < m m seq ( m ) $\operatorname{seq}^{1-1}(\mathfrak {m})&lt;\mathfrak {m}^\mathfrak {m}\ne \operatorname{seq}(\mathfrak {m})$ ” are provable for an arbitrary infinite cardinal m $\mathfrak {m}$ , and these are the best possible results, in the Zermelo-Fraenkel set theory ( ZF $\mathsf {ZF}$ ) without the Axiom of Choice. Also, we show that it is relatively consistent with ZF $\mathsf {ZF}$ that there exists an infinite cardinal m $\mathfrak {m}$ such that S ( m ) = I ( m ) < J ( m ) $S(\mathfrak {m})=I(\mathfrak {m})&lt;J(\mathfrak {m})$ where S ( m ) $S(\mathfrak {m})$ denotes the cardinality of the set of bijections on a set which is of cardinality m $\mathfrak {m}$ .

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