Nash equilibrium Updated 2025-07-16
The best example to look at first is the penalty kick left right Nash equilibrium.
Then, a much more interesting example is choosing a deck of a TCG competition: Magic: The Gathering meta-based deck choice is a bimatrix game, which is the exact same, but each player has N choices rather than 2.
The next case that should be analyzed is the prisoner's dilemma.
The key idea is that:
  • imagine that the game will be played many times between two players
  • if one player always chooses one deck, the other player will adapt by choosing the anti-deck
  • therefore, the best strategy for both players, is to pick decks randomly, each with a certain probability. This type of probabilistic approach is called a mixed strategy
  • if any player deviates from the equilibrium probability, then the other player can add more of the anti-deck to the deck that the other player deviated, and gain an edge
    Therefore, using equilibrium probabilities is the optimal way to play
Natural language processing Updated 2025-07-16
An impossible AI-complete dream!
It is impossible to understand speech, and take meaningful actions from it, if you don't understand what is being talked about.
And without doubt, "understanding what is being talked about" comes down to understanding (efficiently representing) the geometry of the 3D world with a time component.
Not from hearing sounds alone.
Developmental genetics Updated 2025-07-16
How genes form bodies.
Video 1.
Developmental Genetics 1 by Joseph Ross (2020)
Source. Talks about homeobox genes.
Dharma name Updated 2025-07-16
法 (fa3) is the Chinese name for Dharma, and sometimes used as a way short way to refer to Buddhism.
Differentiable manifold Updated 2025-07-16
TODO find a concrete numerical example of doing calculus on a differentiable manifold and visualizing it. Likely start with a boring circle. That would be sweet...
Diffie-Hellman key exchange Updated 2025-07-16
Based on the fact that we don't have a P algorithm for the discrete logarithm of the cyclic group as of 2020, but we do have an efficient algorithm for modular exponentiation. But nor do we have proof that one does not exist! Living on the edge as usual for public-key cryptography.
Dimension Updated 2025-07-16
Diophantine equation Updated 2025-07-16
Sometimes systems of Diophantine equations are considered.
Problems generally involve finding integer solutions to the equations, notably determining if any solution exists, and if infinitely solutions exist.
The general problem is known to be undecidable: Hilbert's tenth problem.
The Pythagorean triples, and its generalization Fermat's last theorem, are the quintessential examples.
Dirac Lagrangian Updated 2025-07-16
where:
Remember that is a 4-vetor, gamma matrices are 4x4 matrices, so the whole thing comes down to a dot product of two 4-vectors, with a modified by matrix multiplication/derivatives, and the result is a scalar, as expected for a Lagrangian.
Like any other Lagrangian, you can then recover the Dirac equation, which is the corresponding equations of motion, by applying the Euler-Lagrange equation to the Lagrangian.

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