For the Porter stemmer rule group shown above $($From Porter, Martin F$.1980.$ An algorithm for suffix stripping. Program $14(3)$:$130-137)$:

$1.$ What is the purpose of including an identity rule such as $\backslash (\backslash$mathrm$\{$SS$\}\backslash$rightarrow $\backslash$mathrm$\{$SS$\}\backslash )?$

$2.$ Applying just this rule group, what will the following words be stemmed to$?$

$-$ circus

$-$ canaries

$-$ boss

$3.$ What rule should be added to correctly stem pony?

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