Changes

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<li>

<p>The ''concatenation'' of the sequence of <math>k\!</math> strings <math>s_1, \ldots, s_k\!</math> can now be defined as an iterated precatenation over the sequence of <math>k + 1\!</math> strings that begins with the string <math>s_0 = \operatorname{Conc}^0 \, = \, ^{\backprime\backprime\prime\prime}</math> and then continues on through the other <math>k\!</math> strings:</p></li>

<p>The ''concatenation'' of the sequence of <math>k\!</math> strings <math>s_1, \ldots, s_k\!</math> can now be defined as an iterated precatenation over the sequence of <math>k+1\!</math> strings that begins with the string <math>s_0 = \operatorname{Conc}^0 \, = \, ^{\backprime\backprime\prime\prime}</math> and then continues on through the other <math>k\!</math> strings:</p></li>

<ol style="list-style-type:lower-roman">

<ol style="list-style-type:lower-roman">

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<p><math>\operatorname{Conc}^0_j s_j \ = \ \operatorname{Conc}^0 \ = \ ^{\backprime\backprime\prime\prime}.</math></p></li>

<p><math>\operatorname{Conc}_{j=0}^0 s_j \ = \ \operatorname{Conc}^0 \ = \ ^{\backprime\backprime\prime\prime}.</math></p></li>

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<p>For <math>k > 0,\!</math></p>

<p>For <math>\ell > 0,\!</math></p>

<p><math>\operatorname{Conc}^k_j s_j \ = \ \operatorname{Prec}(\operatorname{Conc}^{k-1}_j s_j, s_k).</math></p></li>

<p><math>\operatorname{Conc}_{j=1}^\ell s_j \ = \ \operatorname{Prec}(\operatorname{Conc}_{j=0}^{\ell - 1} s_j, s_\ell).</math></p></li>

</ol></ol>

</ol></ol>