Logical conjunction

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The English word "conjuction" comes, through French, from the Latin word "coniungere" ≈ "join".
The logical conjunction of two operands is true if (and only if) both operands are true. The logical conjunction "and" is the same as the natural language "and".

Example: To graduate, you must take and pass both MA101 (Math 101) and EN101 (English 101) and some others, ignored here. That is, you must take both courses to graduate.

There are other logical operators for two-valued logic that are not needed here.

More: Two-valued logic: Operators

The conjunction of two planets happens when the two planets are both in-line with the sun.

Example: Conjunction of Venus and the Earth.

Conjoined twins are born joined at some part of their body.

Job 38:31 Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion? [kjv]

συνηκας δε δεσμον πλειαδος και φραγμον ωριωνος ηνοιξας [lxx]

… coniungere … Pliadis … Arcturi … [v]

The logical conjunction of two operands is true if (and only if) both operands are true.
The English word "conjuction" comes, through French, from the Latin word "coniungere" ≈ "join".

Job 38:31

All

KJV: Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion?

Hebrew: התקשר מעדנות כימה או משכות כסיל תפתח׃

Greek: συνηκας δε δεσμον πλειαδος και φραγμον ωριωνος ηνοιξας

Latin: numquid coniungere valebis micantes stellas Pliadis aut gyrum Arcturi poteris dissipare

Wycliffe: Whether thou schalt mowe ioyne togidere schynynge sterris Pliades, ethir thou schalt mowe distrie the cumpas of Arturis?

Luther: Kannst du die Bande der sieben Sterne zusammenbinden, oder das Band des Orion auflösen?

Job 38:31 Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion? [kjv]

συνηκας δε δεσμον πλειαδος και φραγμον ωριωνος ηνοιξας [lxx]

… coniungere … Pliadis … Arcturi … [v]

The constellation Orion and the Pleiades are more related than they appear in the sky.

Details are left as a future topic.

Logical expressions deal with how the logical values True and False are combined.

False And False is False
False And True is False
True And False is False
True And True is True

Some other symbols for And:

∧ (math notation), ∩ (set notation, intersection)
&& (C-based languages , & is the bitwise conjunction)
and (Python, Lua, Pascal, etc.)

The conjunction or intersection of A & B or A and B is true=1 if both of A and B are true=1, else the result is false=0.

Venn diagram	Expression tree	Extended truth table
	$Expression tree for A & B$	A B \| A & B ----------- 0 0 \| 0 0 0 0 1 \| 0 0 1 1 0 \| 1 0 0 1 1 \| 1 1 1

The word "and" is a conjunction in that both parts (on either side) are needed.

Example: You need to buy milk and cookies at the store.
Distribute as follows.

You need to buy milk at the store and
you need to buy cookies at the store.

You need to do both.

Logical conjunction (i.e., "And", "&", etc.) is related to the intersection operation of sets.
Here is a mathematical definition of set intersection.

Note how the set intersection operator "∩" and the logical conjunction symbol "∧" are related. They are wide at the bottom and narrow/close at the top. This did not just happen. They are related.