TODOs on notes.

notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json

@@ -157,7 +157,7 @@
     "posix/index.md": "97b1b8ecb9a953e855a9acf0ab25b8c8",
     "posix/signals.md": "f4132369878c683bfac4d7fd863d19ba",
     "templates/daily.md": "7866014e730e85683155207a02e367d8",
-    "posix/regexp.md": "cb53e537fc10ce83307f35497d48179f",
+    "posix/regexp.md": "887711b8fc64ca258d9987133ecf056c",
     "journal/2024-02-04.md": "e2b5678fc53d7284b71ed6820c02b954",
     "gawk/regexp.md": "d9229f1eabe1b99e965eecaa03bee86c",
     "_templates/daily.md": "bfcd221502a23a285af100317b6ef127",
@@ -328,7 +328,7 @@
     "_journal/2024-03-22.md": "8da8cda07d3de74f7130981a05dce254",
     "_journal/2024-03/2024-03-21.md": "cd465f71800b080afa5c6bdc75bf9cd3",
     "x86-64/declarations.md": "75bc7857cf2207a40cd7f0ee056af2f2",
-    "x86-64/instructions.md": "a9fa4596009395c4161fd8601a669c6c",
+    "x86-64/instructions.md": "f463916644562db3160a24fad233eb25",
     "git/refs.md": "e20c2c9b14ba6c2bd235416017c5c474",
     "set/trees.md": "c29347ec0ac2e8d5339514c869ecaedf",
     "_journal/2024-03-24.md": "1974cdb9fc42c3a8bebb8ac76d4b1fd6",
@@ -448,12 +448,14 @@
     "_journal/2024-05-18.md": "c0b58b28f84b31cea91404f43b0ee40c",
     "hashing/direct-addressing.md": "17daf22ed3dfcc465924a175e8f11ce3",
     "hashing/index.md": "340f8583eb51eaef011e3302bddb7ff8",
-    "set/classes.md": "c933ca5dfebc3a0298e8ad948c6877a3",
+    "set/classes.md": "3600fde1c4b30f600862d8d640962e4f",
     "_journal/2024-05-19.md": "fddd90fae08fab9bd83b0ef5d362c93a",
     "_journal/2024-05/2024-05-18.md": "c0b58b28f84b31cea91404f43b0ee40c",
     "_journal/2024-05/2024-05-17.md": "fb880d68077b655ede36d994554f3aba",
-    "_journal/2024-05-20.md": "350024abe16438d4cdd2ceaf95cb53c4",
-    "_journal/2024-05/2024-05-19.md": "fc14fc23d4ddca3628df7eec71a07e27"
+    "_journal/2024-05-20.md": "d58a4ecd3bf9621cbe688f043be61239",
+    "_journal/2024-05/2024-05-19.md": "fc14fc23d4ddca3628df7eec71a07e27",
+    "_journal/2024-05-21.md": "4753ad41a519241d1ab7610bfe3c4038",
+    "_journal/2024-05/2024-05-20.md": "d58a4ecd3bf9621cbe688f043be61239"
   },
   "fields_dict": {
     "Basic": [

notes/_journal/2024-05-21.md

@@ -0,0 +1,13 @@
+---
+title: "2024-05-21"
+---
+
+- [x] Anki Flashcards
+- [x] KoL
+- [ ] Sheet Music (10 min.)
+- [ ] Go (1 Life & Death Problem)
+- [ ] Korean (Read 1 Story)
+
+* TODO: Hash tables
+* TODO: Arbitrary unions and intersections
+* TODO: Distributitivity of Disjunction

notes/_journal/2024-05/2024-05-20.md

@@ -9,4 +9,5 @@ title: "2024-05-20"
 - [ ] Korean (Read 1 Story)
 
 * Flashcards for x86-64 [[instructions#Shift Operations|shift operations]].
-* Flashcards on the [[pred-trans#Law of Monotonicity|Law of Monotonicity]].
+* Flashcards on the [[pred-trans#Law of Monotonicity|Law of Monotonicity]].
+* Notes on the "set" of all sets.

notes/posix/regexp.md

@@ -227,14 +227,6 @@ Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 202
 <!--ID: 1707050923689-->
 END%%
 
-%%ANKI
-Basic
-What interval expression repetition counts lead to undefined behavior?
-Back: Counts greater than `255`.
-Reference: Robbins, Arnold D. “GAWK: Effective AWK Programming,” October 2023. [https://www.gnu.org/software/gawk/manual/gawk.pdf](https://www.gnu.org/software/gawk/manual/gawk.pdf)
-<!--ID: 1707050923695-->
-END%%
-
 * `|` is the **alternation operator**. It allows specifying match alternatives.
 
 %%ANKI

notes/set/classes.md

@@ -114,6 +114,30 @@ Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Pre
 <!--ID: 1715970576782-->
 END%%
 
+%%ANKI
+Basic
+What kind of formulas are permitted in the entrance requirement of set-builder notation?
+Back: Well-formed formulas in predicate logic.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736452-->
+END%%
+
+%%ANKI
+Basic
+*Why* do we require first-order logic in the entrance requirement of set-builder notation?
+Back: To avoid any ambiguity introduced by plain English.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736482-->
+END%%
+
+%%ANKI
+Basic
+When is plain English permitted in the entrance requirement of set-builder notation?
+Back: When the English can be translated into predicate logic.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736487-->
+END%%
+
 ## Russell's Paradox
 
 Let $R = \{x \mid x \not\in x\}$. Then $R \in R \Leftrightarrow R \not\in R$.
@@ -270,6 +294,86 @@ Reference: “Russell’s Paradox,” in *Wikipedia*, April 18, 2024, [https://e
 <!--ID: 1716075743555-->
 END%%
 
+%%ANKI
+Basic
+Let $A$ be a set. What does $\{x \in A \mid x \not\in x\}$ evaluate to?
+Back: $A$.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736492-->
+END%%
+
+%%ANKI
+Basic
+*Why* does $A = \{x \in A \mid x \not\in x\}$?
+Back: No set is a member of itself.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736497-->
+END%%
+
+%%ANKI
+Basic
+What two sets are used in the proof of "no set contains all sets"?
+Back: An arbitrary set $A$ and $\{x \in A \mid x \not\in x\}$.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736501-->
+END%%
+
+%%ANKI
+Basic
+Let $B = \{x \in A \mid x \not\in x\}$. What biconditional proves $B \not\in A$?
+Back: $B \in B \Leftrightarrow B \in A \land B \not\in B$
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736505-->
+END%%
+
+%%ANKI
+Basic
+Let $B = \{x \in A \mid x \not\in x\}$. What biconditional proves $B \in A$?
+Back: N/A.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736510-->
+END%%
+
+%%ANKI
+Basic
+Which paradox is used in the proof of "no set contains all sets"?
+Back: Russell's paradox.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736514-->
+END%%
+
+%%ANKI
+Basic
+Which axiom is used in the proof of "no set contains all sets"?
+Back: The subset axiom(s).
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736518-->
+END%%
+
+%%ANKI
+Basic
+Let $B = \{x \in A \mid x \not\in x\}$. What contradiction arises when $B \in B$?
+Back: $B \in A \land B \not\in B$.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736522-->
+END%%
+
+%%ANKI
+Basic
+Let $B = \{x \in A \mid x \not\in x\}$. What contradiction arises when $B \not\in A \land B \not\in B$?
+Back: N/A.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736526-->
+END%%
+
+%%ANKI
+Basic
+Let $B = \{x \in A \mid x \not\in x\}$. What contradiction arises when $B \in A \land B \not\in B$?
+Back: $B \in B$.
+Reference: Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).
+<!--ID: 1716237736529-->
+END%%
+
 ## Bibliography
 
 * Herbert B. Enderton, *Elements of Set Theory* (New York: Academic Press, 1977).

notes/x86-64/instructions.md

@@ -825,8 +825,8 @@ END%%
 
 %%ANKI
 Basic
-What combination of source and destination types is prohibited in unary instructions?
-Back: A source and destination memory address.
+What source/destination types are permitted in unary instructions?
+Back: Registers and memory addresses.
 Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
 <!--ID: 1716125986904-->
 END%%