function c = unique_stable(a)
	[c, ~, ic] = unique(a);
	ia = arrayfun(@(n) find(ic == n)(1), 1:numel(c));
	c = a(sort(ia));
end
function b = unionize_if_intersect(b)
	if size(b, 1) < 2, return, end
	for i = 1:size(b, 2)
		k = find(b(:, i));
		if 1 < numel(k)
			b(k(1), :) = any(b(k, :));
			b(k(2:end), :) = [];
		end
	end
end
function c = f(a)
	u = unique_stable(cell2mat(cellfun(@(s) {strsplit(s, "=")}, a)));
	s2b = @(s) any(cell2mat(cellfun(@(k) {strcmp(u, k)}, strsplit(s, "=")')));
	b = unionize_if_intersect(cell2mat(cellfun(@(s) {s2b(s)}, a')));
	c = arrayfun(@(r) {u(b(r, :))}, 1:size(b, 1)');
end
a = {"a1=a2", "b1=b2", "b3=b2", "c1=c2", "e1=e2", ...
     "a3=a4", "c3=c4", "e1=e3", "a2=a4", "c3=c1", ...
     "b3=a4", "c2=d1", "a4=a5", "d2=c1", "b4=b3", "d3=c3"};
disp(['[' strjoin(cellfun(@(s) {['["' strjoin(s, '", "') '"]']}, f(a)), ', ') ']'])

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