Papa

an early computer chess program written by George Rajna and B. Almasi, in the 70s affiliated with the [|Hungarian Academy of Sciences]. Papa applies the concept of entropy based on own and opponent mobility. It participated at the First World Computer Chess Championship, 1974 in [|Stockholm], unfortunately loosing all its three games due to tactical blunders. Based on preliminary results or expectations, Papa was seeded third, ahead of later winner Kaissa seeded fifth. || toc  =Entropy=
 * Home * Engines * Papa**
 * [[image:WahineTane.jpg link="https://en.wikipedia.org/wiki/File:WahineTane.jpg"]] ||~  || **Papa**,
 * [|Papa and Rangi] ||~  ||^   ||

Rajna
In 2012, George Rajna has re-published a short paper on [|entropy] in chess, which already appeared in //The World Computer-Chess Championship// by Hayes and Levy : ...

Marsland
Tony Marsland mentioned Papa and other programs participating the WCCC 1974 in his handwritten notes on the Hayes and Levy book :

The Merit
The merit of this entropy over the product ratio probably is that it makes a product a sum and a quotient a difference, resulting in Negamax compatible symmetric values around zero in relation to side to move.

> math log({w\over b}) = log(w) - log(b) = -(log(b) - log(w)) = -log({b\over w}) math

=Binary Logarithm= The definition of the amount of [|self-information] and [|information entropy] involves the [|binary logarithm]. On x86 or x86-64, Log2 (lb) may be applied using MMX or SSE2 instructions, with vectors of two or four floats.

> math lb(x) = {ln(x)\over ln(2)} = {log(x)\over log(2)} math

 =Selected Games= WCCC 1974, round 3, Papa - Ribbit : code [Event "WCCC 1974"] [Site "Stockholm, Sweden"] [Date "1974.08.07"] [Round "3"] [White "Papa"] [Black "Ribbit"] [Result "0-1"]
 * [[image:log2.JPG link="https://en.wikipedia.org/wiki/File:Binary_logarithm_plot.png"]] ||
 * Plot of Log2 (lb) ||

1.Nf3 d5 2.d4 Nc6 3.Ne5 Nxe5 4.dxe5 e6 5.e4 dxe4 6.Bb5+ Bd7 7.Bxd7+ Qxd7 8.Qxd7+ Kxd7 9.O-O f5 10.Rd1+ Kc6 11.Be3 Bc5 12.Bxc5 Kxc5 13.Rd7 Nh6 14.Rxc7+ Kb6 15.Rxg7 Ng4 16.f4 exf3 17.gxf3 Nxe5 18.Nd2 Rag8 19.Nc4+ Nxc4 20.Rg6 hxg6 21.Rd1 Rgd8 22.Rxd8 Rxd8 23.a3 Nxb2 24.a4 Nxa4 25.c3 Nxc3 26.f4 Nd5 27.Kf2 Nxf4 28.Kf3 e5 29.h4 Rd4 30.Kg3 Nh5+ 31.Kf2 Rxh4 0-1 code

=See also=
 * Eden
 * Gaia
 * Genesis by Claudio Bollini
 * Genesis by Omid David
 * Genesis by Eric van Riet Paap
 * Mythology
 * Paradise
 * Terra

=External Links=

Chess Program

 * [|Papa's ICGA Tournaments]
 * [|The chess games of Papa (Computer)] from [|chessgames.com]

Papa
> media type="youtube" key="0bumF2HKCto"
 * [|Papa (disambiguation) from Wikipedia]
 * [|Rangi and Papa from Wikipedia]
 * [|Earth Mother from Wikipedia]
 * [|Creation myth from Wikipedia]
 * Johnny Winter - [|Sweet Papa John], September 14, 1975, at [|Swing Auditorium], [|San Bernardino, California], [|YouTube] Video

Entropy

 * [|Entropy from Wikipedia]
 * [|Entropy (disambiguation) from Wikipedia]
 * [|Entropy (statistical thermodynamics) from Wikipedia]
 * [|Entropy (information theory) from Wikipedia]
 * [|Entropy in thermodynamics and information theory from Wikipedia]
 * [|Principle of maximum entropy from Wikipedia]
 * [|Maximum entropy probability distribution from Wikipedia]

=References= =What links here?= include page="Papa" component="backlinks" limit="40"
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