commit 86aa6f41ebb82d0e40ee3dd9f7d2c9dea8b45abd
parent 3a96dc1df078b43f79a94591e175a95bc4042fdc
Author: thing1 <thing1@seacrossedlovers.xyz>
Date: Tue, 27 Jan 2026 12:57:16 +0000
added notes from the 27th
Diffstat:
4 files changed, 51 insertions(+), 6 deletions(-)
diff --git a/CS10720/26.01.26.md b/CS10720/26.01.26.md
@@ -0,0 +1,3 @@
+# 26/01/26
+
+
diff --git a/CS10720/27.01.26.md b/CS10720/27.01.26.md
@@ -0,0 +1,22 @@
+# 27/01/26
+
+## notation
+
+- a set is an unordered collection of unique things
+ - it can be empty (written as phi)
+ - it can be finite, or infinite, so it can be any length or no length
+ - items in a set are called elements, use the funny E to say a element is in a set
+ - sets can be made from other set, for example
+ - A = {dog, cat mouse}
+ - B = {w E A | w contains the letter o}
+ - B = {dog, mouse}
+ - cardinality means the number of elements in a set
+ - a subset means that all elements of one set are contained within another
+ - subset's can be written with a sideways U operator, and a condition can be given by iff
+ - a proper subset is where you have a subset that is not equal to the parent set
+ - superset is the opposite of subset
+ - set difference is the elements which exist only in set A, and is given by a backslash, or somethings subtract
+ - the cartesian product, makes a new set which contain paired items, of the items from each set
+ - 0 is not in the natural numbers, unless it is N sub 0
+ - R sup + is the positive real numbers, and R sup - is the opposite
+ - see https://www.probabilitycourse.com/chapter1/1_2_2_set_operations.php for an example of the repeated union of sets
diff --git a/CS12320/27.01.26.md b/CS12320/27.01.26.md
@@ -0,0 +1,26 @@
+# 27/01/26
+
+# classes
+
+- a class is a blueprint for a specific object
+- generally objects start with uppercase letters
+
+# class diagrams
+
+- '-' minus means private
+- '+' plus means public
+
+# java
+
+- the name of the 'main' class must be the name of the file
+
+```
+public class helloworld {
+ public static void main(String args[]) {
+ System.out.println("hello world!");
+ }
+}
+```
+
+- the java build system is `javac` -> `java` -> it runs
+- you can use the `new` keyword to make an instance of a class
diff --git a/CS12320/practice/helloworld/helloworld.java b/CS12320/practice/helloworld/helloworld.java
@@ -1,11 +1,5 @@
class helloworld {
public static void main(String args[]) {
System.out.println("I was given: " + args.length + " arguments");
-
- System.err.println("AHHH");
-
- int i = 1;
- for (String arg : args)
- System.out.println("Argument " + i++ + " is " + arg);
}
}
