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Wednesday, September 21, 2005

 

λ - Negation

Given:
T ≡ λxy.x
F ≡ λxy.y
~ ≡ λx.x(λuv.v)(λab.a)
What is ~T ?
~T = (λx.x(λuv.v)(λab.a))(λcd.c)
(λcd.c)(λuv.v)(λab.a) = TFT
λuv.v = F
Hence ~T = F

Conversely, what is ~F ?
~F = (λx.x(λuv.v)(λab.a))(λcd.d)
(λcd.d)(λuv.v)(λab.a) = FFT
λab.a = T
Hence ~F = T

Tuesday, September 20, 2005

 

Multiplication gone mad with Lambda Calculus

Let's continue on the madness. The multiplication of two numbers x and y can be computed using the lambda function:
(λxyz.x(yz))
What is (λxyz.x(yz))22 ?
(λxyz.x(yz))22
(λyz.2(yz))2
(λz.2(2z))

λz.(λxy.x(x(y)))((λuv.u(u(v)))z)
λz.(λxy.x(x(y)))(λv.z(z(v)))

λz.(λy.(λv.z(z(v)))((λv.z(z(v)))(y)))
λz.(λy.(λv.z(z(v)))(z(z(y))))
λz.(λy.(z(z(z(z(y))))))
λzy.(z(z(z(z(y))))) = 4

 

Addition gone mad with Lambda Calculus

In Lambda Calculus, natural numbers can be defined as:
0 ≡ λs.(λz.z) ≡ λsz.z
1 ≡ λsz.s(z)
2 ≡ λsz.s(s(z))
3 ≡ λsz.s(s(s(z))) and so on.
Given the successor function: S ≡ λwyx.y(wyx), what is 2S3 ?
2S3 = (λsz.s(sz))(λwyx.y(wyx))(λuv.u(u(uv)))
(λz.(λwyx.y(wyx))((λwyx.y(wyx))z))(λuv.u(u(uv)))
(λwyx.y(wyx))((λwyx.y(wyx))(λuv.u(u(uv)))) = S(S3)

S3 = (λwyx.y(wyx))(λuv.u(u(uv)))
λyx.y((λuv.u(u(uv)))yx)
λyx.y((λv.y(y(yv)))x)
λyx.y(y(y(yx))) = 4

S(S3) = S4 = (λwyx.y(wyx))(λuv.u(u(u(uv))))
λyx.y((λuv.u(u(u(uv))))yx)
λyx.y((λv.y(y(y(yv))))x)
λyx.y(y(y(y(yx)))) = 5
Hence 2S3 = S(S3) = S4 = 5

Monday, September 19, 2005

 

Conceptual Graphs

[Theory: [Graph: {*}]->(Attr)->[Conceptual]]->(Attr)->[Nice]

Tuesday, September 13, 2005

 

E3 Visa for Australians


Monday, September 12, 2005

 

H1B Wages Online

Pretty amazing. Companies in the US are now required to report all the H1B foreign worker wages to the Department of Labor, and get published online to the world! You can find the search engine here.

Some Interesting findings for the highest paid H1B Software practitioners in year 2003:

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