The Mishnah said that on Erev Tish'ah b'Av, a person may not eat two cooked foods, eat meat or drink wine.

(R. Yehudah): This only refers to after midday, and to the final meal.

Both are intended to work in conjunction leniently - it only applies to the final meal, and only if it is after midday.

There is a Beraisa in accordance with the second statement:

A person may consume meat and wine on Erev Tish'ah b'Av only if he is due to eat another meal.

There is a Beraisa in accordance with the first statement:

On Erev Tish'ah b'Av, a person may not eat two cooked foods, eat meat or drink wine.

(R. Shimon b. Gamliel): He should change his custom.

(R. Yehudah): This means that if he is used to eating two cooked foods, he should only eat one;

If he is used to dining with ten people, he should dine with five;

If he is used to drinking ten cups, he should drink five.

This only refers to after midday, but before midday, everything is allowed.

(Beraisa) (R. Meir): On Erev Tish'ah b'Av, a person may not eat two cooked foods, eat meat or drink wine.

(Chachamim): He should change his custom, and decrease his consumption of meat and wine by half, and have none if he usually has none.

(R. Shimon b. Gamliel): If he is used to having radishes or salted fish or meat as dessert, he may do so.

(Beraisa): For the Seudas ha'Mafsekes of Tish'ah b'Av, one may not eat meat, drink wine, or wash.

For Seudos preceding other fasts, or earlier on Erev Tish'ah b'Av, one may eat meat and drink wine, but one may not wash.

(R. Yishmael citing his father R. Yosi): Whenever it is permitted to eat meat and drink wine, it is permitted to wash.

(Beraisa): All laws that apply to a mourner apply to Tish'ah b'Av:

Aside from eating and drinking, it is forbidden to wash, annoint oneself, wear leather shoes, engage in marital relations, read from Tenach, learn Mishnah, Talmud, Midrash, Halachos, and Agados (as Torah gladdens the heart).

(Tana Kama): One is permitted to study topics with which one is unfamiliar.

One is also permitted to read Kinnos, Iyov, and the sad parts of Yirmiyah.

Children are still required to study.

(R. Yehudah): One is not permitted to study topics with which one is unfamiliar.

One is permitted to read Kinnos, Iyov, and the sad parts of Yirmiyah.

Children do not study.

(Beraisa): A mourner may eat salted meat and drink new wine from the vat.

The meat must have been salted for three days, like the Shelamim.

Wine is considered new from the vat while it is bubbling.

(Beraisa): Wine that is bubbling is not forbidden if left uncovered (snakes will not drink it); it bubbles for three days.

On Erev Tish'ah b'Av, R. Yehudah would have dry bread with salt, sit on the floor between the oven and the stove, eat and drink from a jar of water, and he looked as though a deceased relative was lying in front of him.

(Mishnah): It is permitted to work on Tish'ah b'Av only if such is the local custom.

A Talmid Chacham may never work on Tish'ah b'Av.

(R. Shimon b. Gamliel): Everyone should act as a Talmid-Chacham in this regard.

Also, everyone should act as a Talmid Chachahm with regard to fasting the first fasts for rainfall (see 10b).

(Beraisa) (R. Shimon b. Gamliel): If someone eats and drinks on Tish'ah b'Av, it is as though they did so on Yom Kipur.

(R. Akiva): Someone who works on Tish'ah b'Av will never see a sign of blessing from it.

(Chachamim): Someone who works on Tish'ah b'Av and does not mourn for Yerushalayim will not live to see its rejoicing.

Only someone who mourns for Yerushalayim merits to see its rejoicing.

Someone who eats meat and drinks wine on Tish'ah b'Av is referred to by the Pasuk about sin being on the person's bones.

The Mishnah quoted R. Yehudah that a person should overturn his bed, and the Chachamim disagreed.

When R. Yehudah was asked what pregnant and nursing mothers should do, he replied that he only intended those who are able to sleep on the floor.

(Beraisa): R. Yehudah agreed to the Chachamim for a person who cannot sleep on the floor, and they agreed to him for a person who can.

They differed only with regard to overturning other beds that are not used for sleeping.

(Rava): The Halachah follows the Chachamaim and there was no such agreement with R. Yehudah.

The rejoicement of Yom Kipur is due to it being the day of forgiveness and the day that the Luchos were given.

Question: Why was the fifteenth of Av a festival?

(R. Yehudah citing Shmuel): It is the day on which the tribes were permitted to intermarry.

We see this from the Bnos Tzelafchad, where the prohibition only applied to that generation.

(R. Yosef citing R. Nachman): It is the day on which the tribe of Binyamin was permitted to intermarry with the other tribes.

The ban, due to the episode of the concubine at Givah, only applied to that generation.

(Rabah bar bar Chanah citing R. Yochanan): It is the day on which they realized that the decree of those destined to die in the desert had ended.

Only then did Hash-m continue to speak to Moshe.

(Ulla): It is the day on which Hoshea ben Eilah removed the guards that Yeravam had set up to prevent people going to Yerushalayim for Yom Tov.