Lambdia

Foundations & Logic

13 artículos

The Strike Quietly Absorbed a Square Root

A call whose payoff is the square of the stock minus 100 does not start paying at 100, it starts paying at 10, because the square clears the strike exactly when the stock clears its square root. Placing the kink at the written strike prices the option at essentially zero on a stock at 12, when its real value is 53.8168. The closed form is ordinary Black-Scholes on the transformed asset with a growth term of 4 percent and a strike leg that still discounts at the riskless rate, and the value curve sits above intrinsic everywhere while being shallower than it at the spot in question.

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Twelve Marbles, Three Weighings, and Twenty-Seven Ways to Land

Twenty-four possible answers against 3^3 = 27 outcome sequences leaves just enough room, and four against four splits those answers into exactly 8, 8 and 8. Six against six always tips, so it wastes the level outcome and leaves twelve answers for nine remaining sequences, which makes halving impossible rather than merely slow. The counting argument bounds outcome sequences rather than strategies, so it rules out every adaptive continuation at once, and the explicit schedule closes the positive half.

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The Announcement That Told Nobody Anything

A stranger says out loud what every islander can already see, and ten days later ten people leave. The fact was mutual knowledge all along; what the announcement supplied was the nine levels of nested knowledge above it. An explicit count over 4096 possible worlds settles the induction without trusting it.

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Blue, and the Two Sentences That Contain No Answer

Of the eight colour triples, seven are feasible from a pool of three blue hats and two red. The first silence removes one, the second removes two more, and all four survivors put a blue hat on the third man, which is what makes his answer a deduction rather than a lucky call. A pool sweep shows three blue and two red is the only small pool where the story can happen.

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64 Rings, and 584 Billion Years at One Move a Second

Thirty-two rings really do take 136 years at a move a second, which is what makes doubling it to 272 so tempting. The exact ratio between the two cases factors as two to the thirty-two plus one, so the guess is short by more than four billion times. The article carries the lower bound the recursion alone does not give, and the 2-adic rule for which ring moves when.

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23 personas bastan para un cumpleaños compartido, y 253 parejas lo explican

La respuesta refleja ronda las 180, la mitad del calendario. El umbral real es 23, porque una coincidencia necesita una pareja y 23 personas cargan con 253. El mismo razonamiento sitúa la pregunta « ¿alguien comparte MI cumpleaños? » en 253 personas, once veces más gente, y el umbral en raíz cuadrada que hay detrás de ambas explica que un identificador aleatorio de 64 bits se repita tras cinco mil millones de extracciones y no tras dieciocho trillones.

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