Three trees — three owners
Buy one tree — do you own the ground under it?
Three trees of three people
They combine: plow the whole beis se'ah
it is about the trees, not who owns the ground
General rulethese combine, and one may plow the whole beis se'ah for their sake.
How far apart must the trees be?
Rabban GamlielEnough for the ox to pass through with its gear→ about four amos
Sheviis 1:5
Three Trees of Three Owners
שְׁלֹשָׁה אִילָנוֹת שֶׁל שְׁלֹשָׁה אֲנָשִׁים
שְׁלֹשָׁה אִילָנוֹת שֶׁל שְׁלֹשָׁה אֲנָשִׁים,
הֲרֵי אֵלּוּ מִצְטָרְפִין, וְחוֹרְשִׁין כָּל בֵּית סְאָה בִּשְׁבִילָן.
וְכַמָּה יְהֵא בֵינֵיהֶם,
רַבָּן גַּמְלִיאֵל אוֹמֵר, כְּדֵי שֶׁיְּהֵא הַבָּקָר עוֹבֵר בְּכֵלָיו: