I-1 base, 932

I Ching
and substitution systems, 893

IBM 370 computer
my use of, 854

IBM 7090 computer
and π, 911

ICBMs
radar used by, 970
radars for detecting, 1188

Ice
hopper crystals in, 993
snowflake crystals of, 370

Ice-ray style of Chinese lattice, 874

Icosahedral group, 938

Icosahedral symmetry
in quasicrystals, 994

Icosahedron
clusters in sphere packing, 986
and GoldenRatio, 891

IDEA cryptographic system, 1086

Ideal forms
and Platonism, 1176

Ideal gas
CA idealization of, 446

Idealism
and free will, 1135
and history of universality, 1109
and logic as foundation, 860
and models of math, 1149
and nature of space, 1028
and theories of communication, 1181
and universe as intelligence, 1196

Idealizations
of mathematics, 776
in modelling, 364
and Principle of Computational Equivalence, 728
in traditional science, 736
and ultimate theory of physics, 465

Ideals (algebraic)
as generalizing numbers, 1168

Idempotence
of And, 817
in operator systems, 801
of Or, 817

Identity cellular automaton, 883

Identity function
in combinators, 1122

IEEE floating-point standard
and chaos experiments, 919

If (conditional)
emulated by Gamma, 1129

Illative logic
and symbolic systems, 102

ILLIAC IV
and history of CAs, 877

Illinois, University of, xiii

Illusions
visual, 1076

Image compression
lossless, 560
lossy, 572

Image processing
by averaging, 1073
history of, 1077
and history of 2D CAs, 877, 928
and visual perception, 1076
and Walsh transforms, 1073

Imaginary time formalism, 1043
as example of model feature, 992

Imitation
and bird songs, 1180
see also Emulation

Immune system
and Boolean networks, 936
and combinatorial chemistry, 1194
and growth of animals, 418
randomness in, 970, 1002
shape space in, 1184

Impact craters
as landscape elements, 1001

Implementation
see also Emulation
see also entries for specific systems

Implicants
in Boolean formulas, 1095

Implicational calculus, 803, 1170
models in, 1171
possible models of, 805
theorems in, 813

Implicit rules
constraints as, 210, 940

Implies ()
axioms for, 803
axioms in terms of, 1151
in multivalued logic, 1175
non-confluence of, 1037
non-universality of, 1174
and structure of proofs, 1155
truth tables for, 802

Impossibilities
mathematical, 1137

Impulse response
for additive systems, 952
spectrum of, 1081