Objects

There are a number of important sets:

• Rows: $i\in\{1,\ldots,10\}$.
• Columns: $j\in\{1,\ldots,10\}$.
• Parts: {$\triangle$,$\triangledown$,$\triangleright$,$\triangleleft$,$\square$,$\circledcirc$}.
• Direction: $\{$ across (0), down (1) $\}$.
• Ship Number: $k\in\{$ 1,2,3,4 $\}$.