From 54ac3bc78a453e33723ab852c6e2547c03051502 Mon Sep 17 00:00:00 2001 From: cadake <2419720664@qq.com> Date: Mon, 23 Sep 2024 22:37:45 +0800 Subject: [PATCH 1/2] preface --- Chap1.qmd | 29 +- docs/Chap1.html | 507 ++++++++++++-- docs/Chap2.html | 495 ++++++++++++-- docs/IntroLean.html | 534 ++++++++++++--- docs/index.html | 625 +++++++++++++++--- docs/search.json | 177 ++++- docs/site_libs/bootstrap/bootstrap.min.css | 12 +- .../quarto-syntax-highlighting.css | 34 + index.qmd | 131 +++- 9 files changed, 2171 insertions(+), 373 deletions(-) diff --git a/Chap1.qmd b/Chap1.qmd index 90987d1..ba4e927 100644 --- a/Chap1.qmd +++ b/Chap1.qmd @@ -1,36 +1,37 @@ # Sentential Logic + \markdouble{1 Sentential Logic} Chapter 1 of *How To Prove It* introduces the following symbols of logic: ::: {style="margin: 0% 20%"} -| Symbol | Meaning | -|:------:|:-------:| -| $\neg$ | not | -| $\wedge$ | and | -| $\vee$ | or | -| $\to$ | if ... then | +| Symbol | Meaning | +|:-----------------:|:-----------------------------:| +| $\neg$ | not | +| $\wedge$ | and | +| $\vee$ | or | +| $\to$ | if ... then | | $\leftrightarrow$ | iff (that is, if and only if) | ::: -As we will see, Lean uses the same symbols, with the same meanings. A statement of the form $P \wedge Q$ is called a *conjunction*, a statement of the form $P \vee Q$ is called a *disjunction*, a statement of the form $P \to Q$ is an *implication* or a *conditional* statement (with *antecedent* $P$ and *consequent* $Q$), and a statement of the form $P \leftrightarrow Q$ is a *biconditional* statement. The statement $\neg P$ is the *negation* of $P$. +As we will see, Lean uses the same symbols, with the same meanings. A statement of the form $P \wedge Q$ is called a *conjunction*, a statement of the form $P \vee Q$ is called a *disjunction*, a statement of the form $P \to Q$ is an *implication* or a *conditional* statement (with *antecedent* $P$ and *consequent* $Q$), and a statement of the form $P \leftrightarrow Q$ is a *biconditional* statement. The statement $\neg P$ is the *negation* of $P$. This chapter also establishes a number of logical equivalences that will be useful to us later: -::: {id="prop-laws"} -| Name | | Equivalence | | -|:---------|:-----:|:-----:|:-----:| +::: {#prop-laws} +| Name | | Equivalence | | +|:---------------------|:---------------:|:---------------:|:---------------:| | De Morgan's Laws | $\neg (P \wedge Q)$ | is equivalent to | $\neg P \vee \neg Q$ | -| | $\neg (P \vee Q)$ | is equivalent to | $\neg P \wedge \neg Q$ | +| | $\neg (P \vee Q)$ | is equivalent to | $\neg P \wedge \neg Q$ | | Double Negation Law | $\neg\neg P$ | is equivalent to | $P$ | | Conditional Laws | $P \to Q$ | is equivalent to | $\neg P \vee Q$ | -| | $P \to Q$ | is equivalent to | $\neg(P \wedge \neg Q)$ | +| | $P \to Q$ | is equivalent to | $\neg(P \wedge \neg Q)$ | | Contrapositive Law | $P \to Q$ | is equivalent to | $\neg Q \to \neg P$ | ::: -Finally, Chapter 1 of *HTPI* introduces some concepts from set theory. A *set* is a collection of objects; the objects in the collection are called *elements* of the set. The notation $x \in A$ means that $x$ is an element of $A$. Two sets $A$ and $B$ are equal if they have exactly the same elements. We say that $A$ is a *subset* of $B$, denoted $A \subseteq B$, if every element of $A$ is an element of $B$. If $P(x)$ is a statement about $x$, then $\{x \mid P(x)\}$ denotes the set whose elements are the objects $x$ for which $P(x)$ is true. And we have the following operations on sets: +Finally, Chapter 1 of *HTPI* introduces some concepts from set theory. A *set* is a collection of objects; the objects in the collection are called *elements* of the set. The notation $x \in A$ means that $x$ is an element of $A$. Two sets $A$ and $B$ are equal if they have exactly the same elements. We say that $A$ is a *subset* of $B$, denoted $A \subseteq B$, if every element of $A$ is an element of $B$. If $P(x)$ is a statement about $x$, then $\{x \mid P(x)\}$ denotes the set whose elements are the objects $x$ for which $P(x)$ is true. And we have the following operations on sets: -::: {.quote} +::: quote $A \cap B = \{x \mid x \in A \wedge x \in B\} = {}$ the *intersection* of $A$ and $B$, $A \cup B = \{x \mid x \in A \vee x \in B\} = {}$ the *union* of $A$ and $B$, diff --git a/docs/Chap1.html b/docs/Chap1.html index 6ec40d9..6dccde7 100644 --- a/docs/Chap1.html +++ b/docs/Chap1.html @@ -2,12 +2,12 @@
- + -