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rogueviz:: added Grigorchuk

This commit is contained in:
Zeno Rogue 2019-09-08 12:31:45 +02:00
parent be17f575ca
commit f1eb4b9ab7
2 changed files with 478 additions and 0 deletions

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rogueviz/grigorchuk.cpp Normal file
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// RogueViz - Grigorchuk group
// Copyright (C) 2011-2019 Zeno and Tehora Rogue, see 'hyper.cpp' for details
/** \file rogueviz/grigorchuk.cpp
* \brief Grigorchuk group
*
* This is a visualization of the Grigorchuk group. It is the first known group with
* intermediate growth (i.e., superpolynomial and subexponential).
*
* The implementation is based on:
*
* Rostislav Grigorchuk, Igor Pak,
* Groups of Intermediate Growth: an Introduction for Beginners
* https://arxiv.org/pdf/math/0607384.pdf
*
* which presents the material in a simple way.
*
* This creates a map whose tiles correspond to the elements of the Grigorchuk group.
* More precisely, the tiles correspond to the subgroup of index 2 generated by ac, ca, and b
* (this is "more playable"). The three tiles adjacent to g are gb, gac, and gca.
*
* The 'lines' drawn split each tile into two halves, which correspond to the elements of the
* actual Grigorchuk group (g and ga; ga is the one close to gac).
*
* Every element of the Grigorchuk group has finite order. Therefore, if you choose a specific
* way of travelling (e.g. turn left, go, turn right, go) you will always eventually reach the
* starting point.
*
* Command line options:
*
* -grigorchuk -- play on the Grigorchuk group
* -grig-limit 100000 -canvas G -- color the tiles according to the distance from the starting point
* (i.e., the neutral element), the number is the number of tiles colored
* -grig-nolines -- show no splitting lines (also can be switched in the experiments menu)
* -grig-nolabels -- show no labels (also can be switched in the experiments menu)
*
*/
#include "../hyper.h"
namespace grigorchuk {
using namespace hr;
typedef tuple<bool, string, string> splitter;
void add(string& s, char c) {
if(s.size() == 0) s.push_back(c);
else if(c == s.back()) s.pop_back();
else if(c != 'a' && s.back() != 'a')
s.back() = s.back() ^ c ^ 'd' ^ 'b' ^ 'c';
else s.push_back(c);
}
splitter split(string s) {
bool swapped = false;
string s0, s1;
for(char c: s) {
if(c == 'b') add(s0, swapped?'a':'c'), add(s1, swapped?'c':'a');
if(c == 'c') add(s0, swapped?'a':'d'), add(s1, swapped?'d':'a');
if(c == 'd') add(swapped ? s1 : s0, 'b');
if(c == 'a') swapped = !swapped;
}
return {swapped, s0, s1};
}
splitter split_slow(string s) {
bool swapped = false;
string s0, s1;
for(char c: s) {
if(c == 'b') (s0 += swapped?'a':'c'), (s1 += swapped?'c':'a');
if(c == 'c') (s0 += swapped?'a':'d'), (s1 += swapped?'d':'a');
if(c == 'd') ((swapped ? s1 : s0) += 'b'), ((swapped ? s0 : s1) += '-');
if(c == 'a') swapped = !swapped, s0 += '-', s1 += '-';
}
return {swapped, s0, s1};
}
string reduce(const string& x) {
string res;
for(char c: x) add(res, c);
return res;
}
#define Split(x) auto sw = split(x); auto swapped = get<0>(sw); auto s0 = get<1>(sw); auto s1 = get<2>(sw)
bool empt(const string& x) {
Split(x); // auto [swapped, s0, s1] = split(x);
if(x == "") return true;
if(x == "d") return false;
if(swapped) return false;
return empt(s0) && empt(s1);
}
bool empt_slow(const string& x) {
Split(x); // auto [swapped, s0, s1] = split_slow(x);
printf("%s -> %d %s %s\n", x.c_str(), swapped, s0.c_str(), s1.c_str());
if(x == "") return true;
if(x == "d") return false;
if(swapped) return false;
return empt(s0) && empt(s1);
}
typedef const struct rep* prep;
struct rep {
bool swapped;
prep a0;
prep a1;
mutable char last;
mutable bool visited = false;
mutable int len;
rep(bool s, prep a0, prep a1, char l, bool vis = false) : swapped(s), a0(a0), a1(a1), last(l), visited(vis), len(-1) {}
};
bool operator < (const rep a, const rep b) {
return tie(a.swapped, a.a0, a.a1) < tie(b.swapped, b.a0, b.a1);
}
bool operator == (const rep a, const rep b) {
return tie(a.swapped, a.a0, a.a1) == tie(b.swapped, b.a0, b.a1);
}
rep grig_I = rep{false, &grig_I, &grig_I, 0, false};
extern rep grig_a, grig_b, grig_c, grig_d;
rep grig_a = rep{true, &grig_I, &grig_I, 'a', false};
rep grig_b = rep{false, &grig_a, &grig_c, 'b', false};
rep grig_c = rep{false, &grig_a, &grig_d, 'c', false};
rep grig_d = rep{false, &grig_I, &grig_b, 'd', false};
// (ab) c = a (a,c) (a,d) = a(a,c) (a,d) =
map<rep, char> all_reps; // = {grigid, &grigid};
prep lookup(rep x) {
if(x == grig_I) return &grig_I;
else if(x == grig_a) return &grig_a;
else if(x == grig_b) return &grig_b;
else if(x == grig_c) return &grig_c;
else if(x == grig_d) return &grig_d;
else if(all_reps.count(x)) return &(all_reps.find(x)->first);
else return &(all_reps.emplace(x, 0).first->first);
}
/*prep add_a(prep x) {
return lookup({!x->swapped, x->a0, x->a1, 'a'});
}
prep add_d(prep x) {
if(x == &grig_I) return &grig_d;
if(x == &grig_d) return &grig_I;
return lookup({x->swapped, x->swapped?add_d(x->a0):x->a0, x->swapped?x->a1:add_d(x->a1), 'd'});
}
prep add_c(prep x) { return lookup({x->swapped, (x->swapped?add_a:add_d)(x->a0), (x->swapped?add_d:add_a)(x->a1), 'c'}); }
prep add_b(prep x) { return lookup({x->swapped, (x->swapped?add_a:add_c)(x->a0), (x->swapped?add_c:add_a)(x->a1), 'b'}); }
*/
/* ostream& operator << (ostream& os, prep x) {
if(x == &grig_I) return os << "I";
// else if(x == &grig_a) return os << "a";
else if(x == &grig_b) return os << "b";
else if(x == &grig_c) return os << "c";
else if(x == &grig_d) return os << "d";
else {
if(x->swapped) os << "a";
os << "(" << x->a0 << "," << x->a1 << ")";
return os;
}
} */
prep mul (prep x, prep y) {
if(x == &grig_I) return y;
if(y == &grig_I) return x;
if(x == &grig_a && y == &grig_a) return &grig_I;
if(x == &grig_b && y == &grig_b) return &grig_I;
if(x == &grig_c && y == &grig_c) return &grig_I;
if(x == &grig_d && y == &grig_d) return &grig_I;
if(x == &grig_b && y == &grig_c) return &grig_d;
if(x == &grig_c && y == &grig_b) return &grig_d;
if(x == &grig_b && y == &grig_d) return &grig_c;
if(x == &grig_d && y == &grig_b) return &grig_c;
if(x == &grig_c && y == &grig_d) return &grig_b;
if(x == &grig_d && y == &grig_c) return &grig_b;
if(!y->swapped) return lookup(rep{x->swapped, mul(x->a0, y->a0), mul(x->a1, y->a1), y->last});
else return lookup(rep{!x->swapped, mul(x->a1, y->a0), mul(x->a0, y->a1), y->last});
}
string encode(string s) {
if(s == "") return "I";
else if( s == "d") return "d";
else {
Split(s); // auto [swapped, s0, s1] = split(s);
return (swapped ? "a(" : "(") + encode(s0) + "," + encode(s1) + ")";
}
}
set<string> seen;
void addmore(const string& s, int more) {
if(more == 0) {
string sr = s;
reverse(sr.begin(), sr.end());
for(string q: seen) {
string qo = q;
for(char cr: sr) add(q, cr);
if(empt(q)) {
// printf("%s = %s /%s\n", s.c_str(), qo.c_str(), sr.c_str());
return;
}
}
seen.insert(s);
// printf("%s\n", s.c_str());
return;
}
for(char c: {'a', 'b', 'c', 'd'}) {
string s1 = s;
add(s1, c);
if(isize(s1) != isize(s)+1) continue;
addmore(s1, more-1);
}
}
string deform(prep x2) {
string t = "";
while(x2 != &grig_I) {
if(x2->last == 'a') t += 'a', x2 = mul(x2, &grig_a);
else if(x2->last == 'b') t += 'b', x2 = mul(x2, &grig_b);
else if(x2->last == 'c') t += 'c', x2 = mul(x2, &grig_c);
else if(x2->last == 'd') t += 'd', x2 = mul(x2, &grig_d);
else if(x2->last == 'A') t += "ca", x2 = mul(mul(x2, &grig_c), &grig_a);
else if(x2->last == 'C') t += "ac", x2 = mul(mul(x2, &grig_a), &grig_c);
}
reverse(t.begin(), t.end());
return t;
}
bool prepared = false;
prep ac, ca;
int grig_limit = 10000;
void prepare() {
prepared = true;
// rep* grigid = lookup(rep { false, NULL, NULL });
ac = mul(&grig_a, &grig_c);
ca = mul(&grig_c, &grig_a);
// prep where = &grig_I;
string s = "";
/*
for(int a=0; a<=32; a++) {
// printf("%p -> %d %p %p\n", where, where->swapped, where->a0, where->a1);
cout << where << " | " << encode(s) << "\n";
where = ((a&1) ? add_a : add_b) (where);
s += (a&1) ? 'a' : 'b';
}
string test = "ba";
string pw = "";
for(int i=0; i<=16; i++) {
printf("%d: %d\n", i, empt(pw));
pw += test;
}
*/
// printf("TEST %s\n", encode("bcd").c_str());
vector<prep> all;
auto visit = [&] (prep x, char l, int d) {
if(!x->visited) x->visited = true, x->last = l, all.push_back(x), x->len = d;
};
visit(&grig_I, 0, 0);
int length = 0;
int next = all.size();
for(int i=0; i<grig_limit; i++) {
if(i == next) {
printf("%d @ %d\n", i/4, length);
next = all.size(), length++;
}
prep x = all[i];
if(1) {
// printf("%s\n", deform(x).c_str());
}
visit(mul(x, &grig_b), 'b', x->len + 1);
visit(mul(x, ac), 'A', x->len + 1);
visit(mul(x, ca), 'C', x->len + 1);
}
prep test = &grig_b;
test = mul(test, &grig_a);
test = mul(test, &grig_d);
test = mul(test, &grig_a);
test = mul(test, &grig_d);
printf("badad = %s\n", deform(test).c_str());
}
bool view_labels = true, view_lines = true;
}
namespace hr {
struct hrmap_grigorchuk : hrmap_standard {
heptagon *origin;
heptagon *getOrigin() { return origin; }
map<heptagon*, grigorchuk::prep> dec;
map<grigorchuk::prep, heptagon*> enc;
void gtie(heptagon* h, grigorchuk::prep p) {
dec[h] = p;
enc[p] = h;
}
hrmap_grigorchuk() {
if(!grigorchuk::prepared) grigorchuk::prepare();
origin = tailored_alloc<heptagon> (S7);
origin->s = hsOrigin;
origin->emeraldval = 0;
origin->zebraval = 0;
origin->fiftyval = 0;
origin->fieldval = 0;
origin->rval0 = origin->rval1 = 0;
origin->cdata = NULL;
origin->alt = NULL;
origin->c7 = NULL;
origin->distance = 0;
origin->c7 = newCell(3, origin);
gtie(origin, &grigorchuk::grig_I);
}
heptagon *create_step(heptagon *p, int d) {
auto pr = dec[p];
// auto pr1 = pr;
switch(d) {
using namespace grigorchuk;
case 0: pr = mul(mul(pr, &grig_a), &grig_c); break;
case 1: pr = mul(mul(pr, &grig_c), &grig_a); break;
case 2: pr = mul(pr, &grig_b); break;
}
heptagon *h;
if(enc.count(pr)) {
h = enc[pr];
// println(hlog, deform(pr), "*", "acd"[d], " = ", deform(pr1));
}
else {
pr->last = "ACb" [d];
h = tailored_alloc<heptagon> (S7);
h->s = hsOrigin;
h->emeraldval = 0;
h->zebraval = 0;
h->fiftyval = 0;
h->fieldval = 0;
h->rval0 = h->rval1 = 0;
h->cdata = NULL;
h->alt = NULL;
h->c7 = newCell(3, h);
h->distance = p->distance + 1;
gtie(h, pr);
}
h->c.connect(d == 2 ? 2 : 1-d, p, d, false);;
return h;
}
void draw() {
dq::visited_by_matrix.clear();
dq::enqueue_by_matrix(viewctr.at, actualV(viewctr, cview()));
while(!dq::drawqueue.empty()) {
auto& p = dq::drawqueue.front();
heptagon *h = get<0>(p);
transmatrix V = get<1>(p);
dynamicval<ld> b(band_shift, get<2>(p));
bandfixer bf(V);
dq::drawqueue.pop();
cell *c = h->c7;
if(!do_draw(c, V)) continue;
if(grigorchuk::view_lines) queueline(V * ddspin(c, 2) * xpush0(cgi.tessf/2), V * ddspin(c, 2) * xpush0(-cgi.tessf), 0xFF00FFFF, 2);
if(grigorchuk::view_labels) queuestr(V, 0.3, grigorchuk::deform(dec[c->master]), 0xFFFFFF);
drawcell(c, V, 0, false);
for(int i=0; i<3; i++) if(c->move(i))
dq::enqueue_by_matrix(h->cmove(i), V * ddspin(c, i) * xpush(cgi.tessf) * iddspin(c->move(i), c->c.spin(i), M_PI));
}
}
transmatrix relative_matrix(heptagon *h2, heptagon *h1) override {
if(gmatrix0.count(h2->c7) && gmatrix0.count(h1->c7))
return inverse(gmatrix0[h1->c7]) * gmatrix0[h2->c7];
return Id;
}
transmatrix relative_matrix(cell *c2, cell *c1, const struct hyperpoint& hint) override {
if(gmatrix0.count(c2) && gmatrix0.count(c1))
return inverse(gmatrix0[c1]) * gmatrix0[c2];
return Id;
}
};
eGeometry gGrigorchuk(eGeometry(-1));
void create_grigorchuk_geometry() {
if(gGrigorchuk != -1) return;
ginf.push_back(ginf[gNormal]);
gGrigorchuk = eGeometry(isize(ginf) - 1);
variation = eVariation::pure;
auto& gi = ginf[gGrigorchuk];
gi.sides = 3;
gi.vertex = 8;
gi.flags = qANYQ | qEXPERIMENTAL;
gi.tiling_name = "{3,8}";
gi.quotient_name = "Grigorchuk";
gi.shortname = "Grig";
}
int args() {
using namespace arg;
if(0) ;
else if(argis("-grig-limit")) {
shift(); grigorchuk::grig_limit = argi();
}
else if(argis("-grigorchuk")) {
PHASEFROM(3);
stop_game();
create_grigorchuk_geometry();
set_geometry(gGrigorchuk);
set_variation(eVariation::pure);
}
else if(argis("-grig-nolines")) {
grigorchuk::view_lines = false;
}
else if(argis("-grig-nolabels")) {
grigorchuk::view_labels = false;
}
else return 1;
return 0;
}
auto hook = addHook(hooks_args, 100, args)
+ addHook(hooks_newmap, 100, [] { return geometry == gGrigorchuk ? new hrmap_grigorchuk : nullptr; })
+ addHook(patterns::hooks_generate_canvas, 100, [] (cell* c) {
if(patterns::whichCanvas == 'G' && geometry == gGrigorchuk)
return 0x102008 * (1 + ((hrmap_grigorchuk*)currentmap)->dec[c->master]->len);
return -1;
})
+ addHook(dialog::hooks_display_dialog, 100, [] () {
if(current_screen_cfunction() == showEuclideanMenu && geometry == gGrigorchuk) {
dialog::addBoolItem_action(XLAT("Grigorchuk lines"), grigorchuk::view_lines, 'L');
dialog::addBoolItem_action(XLAT("Grigorchuk labels"), grigorchuk::view_labels, 'M');
}
});
}

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@ -2474,3 +2474,4 @@ auto hooks =
#include "magiccube.cpp" #include "magiccube.cpp"
#include "cvl.cpp" #include "cvl.cpp"
#include "newconf.cpp" #include "newconf.cpp"
#include "grigorchuk.cpp"