bak

Author: cirosantilli

accounts.bigb

@@ -165,6 +165,7 @@ Other accounts:
 * https://www.tiktok.com/@cirosantilli2
 * https://www.transifex.com/user/profile/cirosantilli
 * https://www.tripadvisor.com/members/cirosantilli
+* https://www.whatdotheyknow.com/user/ciro_santilli/profile
 
 Profiles without URLs (OMG...):
 * <Discord>: username `cirosantilli`, previously `cirosantilli#8921`

c/Makefile

@@ -2,19 +2,28 @@
 
 # Input parameters
 CC = gcc
-CFLGS = -ggdb3 -O0 -pedantic-errors -std=c99 -Wall -Wextra
+CFLGS = -ggdb3 -O$O -pedantic-errors -std=c11 -Wall -Wextra
 IN_EXT = .c
+O = 0
 OUT_DIR = .
 OUT_EXT = .out
 
+-include Makefile_params
+
 OUTS = $(addprefix $(OUT_DIR)/, $(addsuffix $(OUT_EXT), $(basename $(wildcard *$(IN_EXT)))))
 
 .PHONY: all clean mkdir test
 
 all: mkdir $(OUTS)
 
 $(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT)
-	$(CC) $(CFLGS) -o '$@' '$<'
+	$(CC) $(CFLGS) -o '$@' '$<' $(LIBS)
+
+$(OUT_DIR)%$(OUT_EXT): $(IN_DIR)%$(CXX_EXT) $(ALL_DEPEND)
+	$(CXX) $(CXXFLAGS) -o '$@' '$<' $(LIBS)
+
+$(OUT_DIR)%$(OUT_EXT): $(IN_DIR)%$(FF_EXT) $(ALL_DEPEND)
+	$(FF) $(FFLAGS) -o '$@' '$<' $(FFLIBS)
 
 clean:
 	if [ '$(OUT_DIR)' = '.' ]; then \
@@ -34,3 +43,5 @@ test: all
 		exit 1;\
 	  fi;\
 	done;\
+
+-include Makefile_targets

calculus.bigb

@@ -518,7 +518,7 @@ Sample software implementations:
 \Image[https://raw.githubusercontent.com/cirosantilli/media/master/home/numpy/fft_plot.svg]
 {title=<DFT> of $2 \sin(t) + \cos(4t)$ with 25 points}
 {disambiguate=Discrete Fourier transform}
-{description=This is a simple example of a <discrete Fourier transform>. It also illustrates how the <discrete Fourier transform of a real signal> is symmetric around the center point.}
+{description=This is a simple example of a <discrete Fourier transform> for a real input signal. It illustrates how the <DFT> takes N <complex numbers> as input, and produces N <complex numbers> as output. It also illustrates how the <discrete Fourier transform of a real signal> is symmetric around the center point.}
 {height=600}
 
 = Discrete Fourier transform of a real signal

cia-2010-covert-communication-websites.bigb

@@ -4748,6 +4748,7 @@ Many hits appear to happen on the same days, and per-day data does exist: https:
 
 = viewdns.info
 {parent=Data sources}
+{tag=Data as a service}
 
 Accounts used so far: 6 (1500 reverse IP checks).
 

ciro-santilli.bigb

@@ -66,6 +66,11 @@ Ciro once saw some cartoon on <Wikipedia> help pages of a turtle with a book in
 Another analogous version of this fantasy more in touch with Ciro's <sinophily> is the ideal of the <Chinese scholar>, notably including their stereotypical attributes such as mastery of the <Four Arts>.
 }
 
+\Image[https://raw.githubusercontent.com/cirosantilli/media/master/Ciro_Santilli_as_a_child_buliding_with_boxes.jpg]
+{height=700}
+{title=<Ciro Santilli> piling boxes as a child}
+{description=A natural born <engineer>.}
+
 \Include[sponsor]
 \Include[the-most-important-projects-done-by-ciro-santilli]
 \Include[todo]

computer-science.bigb

@@ -110,6 +110,13 @@ Coolest ones besides the obvious boring <halting problem>:
 * <mortal matrix problem>
 * <Diophantine equation> existence of solutions: <undecidable Diophantine equation problems>
 
+= Undecidability requires infinitely many inputs
+{parent=Undecidable problem}
+
+If there are infinitely many inputs, we can always construct a (potentially exponentially huge) <Turing machine> that hardcodes the outcome for every possible input, so the problem is never <undecidable>.
+
+The problem is of course deciding and proving the outcome for each possible input, notably as it is possible that calculation for some of the inputs may be <independent (mathematical logic)> from <ZFC>.
+
 = Mortal matrix problem
 {parent=Undecidable problem}
 
@@ -301,9 +308,6 @@ The Busy Beaver problem is cool because it puts the <halting problem> in a more
 Bibliography:
 * https://www.scottaaronson.com/blog/?p=4916
 * https://www.quantamagazine.org/the-busy-beaver-game-illuminates-the-fundamental-limits-of-math-20201210
-* https://cs.stackexchange.com/questions/59344/what-are-very-short-programs-with-unknown-halting-status
-  * https://cs.stackexchange.com/questions/44869/what-are-the-simplest-examples-of-programs-that-we-do-not-know-whether-they-term imprecise duplicate
-* https://cstheory.stackexchange.com/questions/20978/what-is-the-smallest-turing-machine-where-it-is-unknown-if-it-halts-or-not
 
 = Step busy beaver
 {parent=Busy beaver}
@@ -329,6 +333,11 @@ The following things come to mind when you look into research in this area, espe
 * it is largely <recreational mathematics>, i.e. done by non-professionals, a bit like the <aperiodic tiling>. Humbly, they tend to call their results <lemma (mathematics)>[lemmas]
 * complex structure emerges from simple rules, leading to a complex <classification (mathematics)> with a few edge cases, much like the <classification of finite simple groups>
 
+Bibliography:
+* https://cs.stackexchange.com/questions/59344/what-are-very-short-programs-with-unknown-halting-status
+  * https://cs.stackexchange.com/questions/44869/what-are-the-simplest-examples-of-programs-that-we-do-not-know-whether-they-term imprecise duplicate
+* https://cstheory.stackexchange.com/questions/20978/what-is-the-smallest-turing-machine-where-it-is-unknown-if-it-halts-or-not
+
 = Turing machine acceleration
 {c}
 {parent=Specific values of the Busy beaver function}
@@ -437,6 +446,26 @@ https://wiki.bbchallenge.org/wiki/Antihydra[]:
 * https://www.reddit.com/r/math/comments/1dubva0/finding_the_6th_busy_beaver_number_%CF%836_aka_bb6_is/ "Finding the 6th busy beaver number (Σ(6), AKA BB(6)) is at least as hard as a hard Collatz-like math problem called Antihydra":
 * https://www.reddit.com/r/compsci/comments/1duc62e/finding_the_6th_busy_beaver_number_%CF%836_aka_bb6_is/
 
+= Antihydra
+{parent=BB(6) is hard}
+{title2=28 Jun 2024}
+
+https://wiki.bbchallenge.org/wiki/Antihydra
+
+= Antihydra GMP implementation
+{parent=Antihydra}
+{tag=GNU Multiple Precision Arithmetic Library}
+
+= gmp/antihydra.c
+{file}
+{parent=Antihydra}
+{tag=GMP example}
+
+Also posted at:
+* https://wiki.bbchallenge.org/wiki/Antihydra
+* https://cstheory.stackexchange.com/questions/20978/what-is-the-smallest-turing-machine-where-it-is-unknown-if-it-halts-or-not/53326#53326
+* https://cs.stackexchange.com/questions/59344/what-are-very-short-programs-with-unknown-halting-status/162108#162108
+
 = Busy beaver scale
 {parent=Busy beaver}
 
@@ -656,6 +685,15 @@ Like <Binary search tree>, but each node can have multiple objects and more than
 = Complexity
 {synonym}
 
+= Time complexity
+{parent=Complexity class}
+{wiki}
+
+= Quasilinear time
+{parent=Time complexity}
+{title2=$O(n \log^k(n))$}
+{wiki}
+
 = Big O notation family
 {parent=Complexity class}