HoldPattern

HoldPattern[expr]
is equivalent to expr for pattern matching, but maintains expr in an unevaluated form.

The left-hand sides of rules are usually evaluated, as are parts of the left-hand sides of assignments. You can use HoldPattern to stop any part from being evaluated.

Set up a pattern whose left-hand side is kept unevaluated:

Use the pattern:

Make a definition without the argument of

being evaluated:

autoevaluates to Log[b]/Log[a], so there is a match:

finds elements that match patt; use HoldPattern to find rules:

Set up a pattern whose left-hand side is kept unevaluated:

Out[1]=

Use the pattern:

Out[2]=

Make a definition without the argument of

being evaluated:

Out[2]=

autoevaluates to Log[b]/Log[a], so there is a match:

Out[1]=

finds elements that match patt; use HoldPattern to find rules:

Out[1]=