Asymmetric Logic-grid "Brentwood Puzzle": What are these people doing?

Question

Three men, including Gianni and three woman, including Sachi are in line at the BrentWood post office. Each has two different pieces of business to conduct.

• The first person is a woman.
• Carlos wants to send an overnight package.
• Lau is just ahead of Pimentelli who is the same sex as Lau.
• Gianni is two places ahead of the person who wants to buy stamps.
• Knutson - who is the opposite sex than Rendler - isn't the person who wanted to complain about a mail carrier.
• The six people, not necessarily in the same order are - Anthony, Donna, the person who wants to fill out a change-of-address form, the one who wants to buy a money order, the one who wants to send Airmail to Tibet and the second person in the line.
• The four tasks of the last two people in line, not necessarily in the same order are - sending books fourth class, buying a money order, picking up a package and complaining about a mail carrier.
• The person who wants to send books fourth class is just behind a person of the same sex.
• Mary is just behind a person who wants to send an insured package.
• The person who wants to send Airmail to Tibet is either two places ahead of or two places behind the one who wants to add postage to his or her meter.
• Anthony isn't two places behind the who wants to pickup a registered letter.
• Toriseza is two places ahead of the person who wants to pick up a package.
• Knutson isn't just ahead of the person who wants to send an item parcel post.

Can you figure out where each customer is in the line, his or her full name (one surname is Loti) and the two things he or she wants to accomplish? Provide your answer is POSITION - FIRST NAME - LAST NAME - BUSINESS - BUSINESS format.

The in general way was to go forward in finding a loophole information which will let us either match someone with job or sex or position but I couldn't do either. Please guide.

Source: I have obtained this puzzle from a book called "400 Puzzles (Infosys)" which is the collection of different variety of puzzles asked in "Interviews of Infosys"

Note: The answer is provided but the the way to arrive at the solution can't be just trial and error method. So if anyone can guide how to proceed rather than just reiterate question I'll be obliged.

Answer 1

Not yet an answer, but just clearing up what is found in the puzzle.

We know that Loti is a surname, but we are not given explicit information on the rest.

We can use social norms to guess that the first names of the men are;

• Gianni
• Carlos
• Anthony

while the women are;

• Sachi
• Donna
• Mary

This leaves the following as last names:

• Lau
• Pimentelli
• Knutson
• Rendler
• Toriseza
• Loti

Is this too presumptuous?

There are 12 tasks. These are;

• Send an overnight package
• Buy stamps
• Complain about the mail carrier
• Fill out a change of address form
• Buy a money order
• Send a airmail to Tibet
• Send books 4th class
• Pick up a package
• Send an insured package
• Add postage to the meter
• Pick up a registered letter
• Send an item parcel post

The clues then are;

1. The first person is a woman.
2. Carlos wants to send an overnight package.
3. Lau is just ahead of Pimentelli.
4. Lau and Pimentelli are the same sex.
5. Gianni is two places ahead of the person who wants to buy stamps.
6. Knutson is the opposite sex of Rendler.
7. Knutson isn't the person who wanted to complain about a mail carrier.
8. The six people, not necessarily in the same order are - Anthony, Donna, the person who wants to fill out a change-of-address form, the one who wants to buy a money order, the one who wants to send Airmail to Tibet and the second person in the line.
9. The four tasks of the last two people in line, not necessarily in the same order are - sending books fourth class, buying a money order, picking up a package and complaining about a mail carrier.
10. The person who wants to send books fourth class is just behind a person of the same sex.
11. Mary is just behind a person who wants to send an insured package.
12. The person who wants to send Airmail to Tibet is either two places ahead of or two places behind the one who wants to add postage to his or her meter.
13. Anthony isn't two places behind the who wants to pickup a registered letter.
14. Toriseza is two places ahead of the person who wants to pick up a package.
15. Knutson isn't just ahead of the person who wants to send an item parcel post.

Answer 2

It is possible to solve this puzzle, using only 2 guesses (in each case between 2 possibilities) using a more or less standard logic grid.

Whether it is possible to solve without guessing, i.e. by using a more clever logic-grid, I don't know.

In any case, here is the solution I found:

Step 1:

Assuming the first names can be directly correlated to the sex of individuals (as posited by @Trenin) and using the clues mentioned in the image above, we get the above result. Notice that on the left side I have introduced an auxilliary grid which keeps tabs on whether a row is Male or Female. Moving on...

Step 2:

Using the clues mentioned above (clue numbers according to @Trenin) we get the above result. The yellow colorings indicate that a single person cannot have both colorings.

Step 3:

I have now introduced another auxilliary box which keeps track of the possible orderings of Males and Females in the line. Yellow rows are not possible. To the right of this box are the clues used for this deduction. At this point I got stuck and had to guess.

Carlos could be in either the 3rd or 4th position and I guessed the 4th:

Step 4:

This quickly led to a contradiction.

The person in the first row must use 2 of the last 3 choices. And the person in the second row must use 1 of the 3 choices. Therefore the person in row 3 must use both "change of address" and "airmail to Tibet", which is not possible. Hence Carlos must be in row 3:

Step 5:

I now got stuck again.

Anthony could be in only 2 positions, so I guessed he was in position 4:

Step 6:

This led to the contradiction shown above.

I.e. clue 12 cannot be fulfilled. Hence, Anthony could only be in position 6. This quickly led to the final solution, shown below:

Step 7:

I'd be very interested to know if assymetric logic grids like this, i.e. where N objects have more than 1 choice each and/or less than N choices each, are possible to set up in a logic grid, similar to normal logic-grids.