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    <p>From the description in the article, your implementation seems correct (the part you mark as "what to do here" should indeed be nothing).</p> <p>If you are having problems with local maxima (something the article claims the coin toss should avoid), make sure your implemenations of Initial, Transpose, ComputePl and Flip are correct. </p> <p>You can also try making the coin tossed biased (increasing the probability of Flip() == 1 will make this closer to a random walk and less susceptible to getting stuck).</p> <p>Here is a slightly tighter version of your code:</p> <pre><code>var current_f = Initial(); // current accepted function f var current_Pl_f = ComputePl(current_f); // current plausibility of accepted function f for (int i = 0; i &lt; 10000; i++) { var candidate_f = Transpose(current_f); // create a candidate function var candidate_Pl_f = ComputePl(candidate_f); // compute its plausibility if (candidate_Pl_f &gt; current_Pl_f || Flip() == 1) { // either candidate Pl has improved, // or it hasn't and we flipped the coin in candidate's favor // - accept the candidate current_f = candidate_f; current_Pl_f = candidate_Pl_f; } } </code></pre>
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    1. POAlgorithm for computing the plausibility of a function / Monte Carlo Method
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    1. USStjepan Rajko
    1. USStjepan Rajko
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    1. COThats much clearer, thanks. One other thing I realized is that the article doesn't really mention whether you should keep track of candidates already attempted and be sure not to repeat them, I imagine that should be the case...I posted in my edit the additional function used for Transposition and computing Pl.
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      1. USSean Thoman
    2. COPerhaps it would be useful to hash certain things about the candidates already attempted (e.g., their plausability - though be careful since the candidate space is **large**), but I don't think you want to eliminate repetition altogether. Even though you have already visited a candidate, the random transpose from that candidate can take you to a previously unvisited candidate. By eliminating repetition, you could even "box yourself in" (be at a candidate where you have already visited all of its transposes).
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      1. USStjepan Rajko
    3. COWith regards to the Transpose() method -- Ive only been passing in one or two int values as the indices argument. Basically more indices would mean a more aggressive shuffling of the dictionary. So typically its just one randomly generated integer that gets passed to that method. Also the alphabet of available chars used contains many chars 'ABCDEFG...' etc, but if the encoded message is just 'bveb' or something, it will only make transpositions for mappings of b -> (), v -> (), e -> (), etc. where () represents any of the possible chars in the alphabet.
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      1. USSean Thoman
 

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