Find an infinite set of (propositional logic) formula, $S$, which satisfies: If you take any $2$ elements from $S$, they are satisfiable. If you take any $3$ elements from $S$, they are unsatisfiable. As an illustration, a finite set of formula $S' = \{a, b \land c, a \implies \neg b\}$ sat...

This next riddle will be a bit more challenging. I am two halves of a whole, For now only some remain. What am I?

I am confused someone asked me to tell the name but finding its difficult he told that it is used in our daily life and hint was only If you will cut me I will make you weeping.

You are trapped in a room. In front of you, there is a table on which there is an infinite number of stacks of cards each containing an infinite number of black or white cards. Two stacks are considered to be "similar" if when you put the stacks side by side, every $n$-th pair of adjacent cards ...

this is my first try on connect walls, please tell me what I can improve on. Thanks! Inspired by I Hope You Like Connect Walls! #2 INSTRUCTIONS: Step 1: Find the hidden word in each word Step 2: Group them into groups Step 3: Find the tag on puzzling.se I am referring to THE WORDS Adona...

There are $5$ rupees on Arnav's table. He knows that exactly $2$ of the rupees are counterfeit. One of these $2$ coins is lighter than a normal (non-counterfeit) rupee, and one of these $2$ coins is heavier than a normal rupee. Arnav conveniently has a balance scale next to him, and he would like...

Out of six numbers in some order, we know third and fourth ranked numbers in every five out of the six numbers. Find the first ranked in the order given. for example, if the rank was the lexicographical rank, Out of the numbers: one, two,..., six. (correct order:- five,four,one,six,three,two) ...

Trying two make three triangles by moving only two sticks.

I did a puzzle that made me calculate the last number, and I couldn't figure it out so I looked at the answer, but still don't understand how I get to that answer. Number sequence is 4 28 68 218 44 46 268 And the following number (the answer) is: 778 How do I get to 778 using all the numbers?

During preparation of a test I am facing problem in solving this non-verbal question. What may the possible solution figure from A,B,C,D?

This chain of numbers is making confused.Help to find the answer with explanation.

[Appeal: I'm trying to figure out a fun puzzle formula. There are many out there ("Who owns the fish", sudoku, etc). I'm interested in feedback on whether this works or is interesting for people. Possible to solve by hand. Techniques you found helpful, etc. Also a rating for this if you solve it:...

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To people are playing a game, in which each player takes turns drawing closed loops on a sheet of paper. Each new loop must intersect each of the other loops exactly twice. When one player has no moves available, the other player wins. Is it possible for any of the player to ever win? If yes, ho...