[Right triangle ⏵ may be expanded, down triangle ⏷ to close. Button = tree pop-up. × = close pop-up.]

Terminal: run. Derivation Graphs: (left-to-right) compact / full; (top-down) full / compact.

Simpler: They are planes

(Chomsky 1956), p118 excerpt. (Click image for page.)

Help: blue = parse inside. Abbr.: WS: Workspace; Initial WS: initial heads for Merge after LEX lookup.

WS n, n = 1,2,... for intermediate stages after Initial WS. Final WS: when WS items converge on a single SO.
Bracketing: {...} (Merge). {...} (FormSet). At Spellout, {...} indicates free word order. [word] indicates word is optionally present.
Head Hd_{selection/features}, e.g. p_θ = predicate head p that seeks a θ-relevant (θR) IA from the WS. p_θ is a θ-seeker (θS).
v_see:θ:pst = head v has complement see, a θR EA from the WS and TNS. v is also a θS.
INFL seeks θR from its complement (not the WS).
Complementizer C comes in different flavors wrt. Force, .e.g. declarative C, interrogative C_Q and relative clause head C_rel.
Features, e.g. TNS pres/pst or DET the/a (shorthand for a bundle of semantic features).
Note: φ-features, e.g. 1sg, appear only at Spellout. Some words do not project, turn into features, e.g. determiners.

Words: they are flying planes

Initial WS 1: planes fly_ø:_presp v_fly:_θ v_v:_prog:_pres INFL_v:_pl they

WS 1: {v_fly:_θ, fly_ø:_presp} planes v_v:_prog:_pres INFL_v:_pl they

WS 2: {planes, {v_fly:_θ, fly_ø:_presp}} v_v:_prog:_pres INFL_v:_pl they

WS 3: {v_v:_prog:_pres, {planes, {v_fly:_θ, fly_ø:_presp}}} INFL_v:_pl they

WS 4: {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, fly_ø:_presp}}}} they

WS 1: {v_fly:_θ, fly_ø:_presp} planes v_v:_prog:_pres INFL_v:_pl they

WS 2: {they, {v_fly:_θ, fly_ø:_presp}} planes v_v:_prog:_pres INFL_v:_pl

WS 3: {v_v:_prog:_pres, {they, {v_fly:_θ, fly_ø:_presp}}} planes INFL_v:_pl

WS 4: {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, fly_ø:_presp}}}} planes

WS 1: {v_fly:_θ, fly_ø:_presp} planes v_v:_prog:_pres INFL_v:_pl they

WS 2: {planes, they} {v_fly:_θ, fly_ø:_presp} v_v:_prog:_pres INFL_v:_pl

WS 3: {{planes, they}, {v_fly:_θ, fly_ø:_presp}} v_v:_prog:_pres INFL_v:_pl

WS 4: {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}} INFL_v:_pl

WS 5: {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}}}

Final WS: {C, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}}}}

INT/EXT: {C, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}}}}

EXT: {planes,[and],they} 3pl pres be ing fly

Spellout: {planes,[and],they} are flying

Blocked: inconsistent with input!

EXT: there 3pl pres be ing {planes,[and],they} fly

Blocked: inconsistent with input!

Final WS: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}}}}

INT/EXT: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, fly_ø:_presp}}}}}

EXT: pl pres be →→ {planes,[and],they} 3pl pres be ing fly

Spellout: 3pl pres be {planes,[and],they} ing fly

Spellout: are {planes,[and],they} flying

Blocked: inconsistent with input!

EXT: pl pres be →→ there 3pl pres be ing {planes,[and],they} fly

Spellout: 3pl pres be there ing {planes,[and],they} fly

Blocked: inconsistent with input!

WS 1: {planes, they} fly_ø:_presp v_fly:_θ v_v:_prog:_pres INFL_v:_pl

Initial WS 2: planes fly_θ:_presp v_fly:_θ v_v:_prog:_pres INFL_v:_pl they

WS 1: {fly_θ:_presp, planes} v_fly:_θ v_v:_prog:_pres INFL_v:_pl they

WS 2: {v_fly:_θ, {fly_θ:_presp, planes}} v_v:_prog:_pres INFL_v:_pl they

WS 3: {they, {v_fly:_θ, {fly_θ:_presp, planes}}} v_v:_prog:_pres INFL_v:_pl

WS 4: {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}} INFL_v:_pl

WS 5: {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}}}

Final WS: {C, {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}}}}

INT/EXT: {C, {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}}}}

EXT: they 3pl pres be ing fly planes

Spellout: they are flying planes

Parse found: they 3pl pres be ing fly planes

EXT: there 3pl pres be ing they fly planes

Blocked: inconsistent with input!

Final WS: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}}}}

INT/EXT: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {they, {v_fly:_θ, {fly_θ:_presp, planes}}}}}}

EXT: pl pres be →→ they 3pl pres be ing fly planes

Spellout: 3pl pres be they ing fly planes

Spellout: are they flying planes

Blocked: inconsistent with input!

EXT: pl pres be →→ there 3pl pres be ing they fly planes

Spellout: 3pl pres be there ing they fly planes

Blocked: inconsistent with input!

WS 1: {fly_θ:_presp, they} planes v_fly:_θ v_v:_prog:_pres INFL_v:_pl

WS 2: {v_fly:_θ, {fly_θ:_presp, they}} planes v_v:_prog:_pres INFL_v:_pl

WS 3: {planes, {v_fly:_θ, {fly_θ:_presp, they}}} v_v:_prog:_pres INFL_v:_pl

WS 4: {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}} INFL_v:_pl

WS 5: {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}}}

Final WS: {C, {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}}}}

INT/EXT: {C, {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}}}}

Error: Case: object "they" not ACC

Final WS: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}}}}

INT/EXT: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {planes, {v_fly:_θ, {fly_θ:_presp, they}}}}}}

Error: Case: object "they" not ACC

WS 1: {planes, they} fly_θ:_presp v_fly:_θ v_v:_prog:_pres INFL_v:_pl

WS 2: {fly_θ:_presp, {planes, they}} v_fly:_θ v_v:_prog:_pres INFL_v:_pl

WS 3: {v_fly:_θ, {fly_θ:_presp, {planes, they}}} v_v:_prog:_pres INFL_v:_pl

WS 4: {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}} v_v:_prog:_pres INFL_v:_pl

WS 5: {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}} INFL_v:_pl

WS 6: {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}}}

Final WS: {C, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}}}}

INT/EXT: {C, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}}}}

EXT: {planes,[and],they} 3pl pres be ing fly {planes,[and],they}

Blocked: EXT inconsistent!

Blocked: inconsistent with input!

EXT: there 3pl pres be ing {planes,[and],they} fly {planes,[and],they}

Blocked: inconsistent with input!

Final WS: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}}}}

INT/EXT: {C_Q:_{aux(pl,pres,be)}, {INFL_v:_pl, {v_v:_prog:_pres, {{planes, they}, {v_fly:_θ, {fly_θ:_presp, {planes, they}}}}}}}

EXT: pl pres be →→ {planes,[and],they} 3pl pres be ing fly {planes,[and],they}

Spellout: 3pl pres be {planes,[and],they} ing fly {planes,[and],they}

Blocked: EXT inconsistent!

Blocked: inconsistent with input!

EXT: pl pres be →→ there 3pl pres be ing {planes,[and],they} fly {planes,[and],they}

Spellout: 3pl pres be there ing {planes,[and],they} fly {planes,[and],they}

Blocked: inconsistent with input!

Initial WS 3: planes flying_θ be_θ v_be:_θ:_pres INFL_v:_pl they

WS 1: {flying_θ, planes} be_θ v_be:_θ:_pres INFL_v:_pl they

WS 1: {flying_θ, they} planes be_θ v_be:_θ:_pres INFL_v:_pl

WS 1: {be_θ, {planes, {flying_θ, planes}}} v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, {planes, {flying_θ, planes}}}} INFL_v:_pl they

WS 3: {they, {v_be:_θ:_pres, {be_θ, {planes, {flying_θ, planes}}}}} INFL_v:_pl

WS 4: {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, {planes, {flying_θ, planes}}}}}}

Final WS: {C, {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, {planes, {flying_θ, planes}}}}}}}

INT/EXT: {C, {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, {planes, {flying_θ, planes}}}}}}}

EXT: they 3pl pres be flying planes

Spellout: they are flying planes

Parse found: they 3pl pres be flying planes

WS 1: {be_θ, {they, {flying_θ, they}}} planes v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, {they, {flying_θ, they}}}} planes INFL_v:_pl

WS 3: {planes, {v_be:_θ:_pres, {be_θ, {they, {flying_θ, they}}}}} INFL_v:_pl

WS 4: {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, {they, {flying_θ, they}}}}}}

Final WS: {C, {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, {they, {flying_θ, they}}}}}}}

INT/EXT: {C, {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, {they, {flying_θ, they}}}}}}}

Error: Case: object "they" not ACC

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they

WS 3: {flying_θ, they} {v_be:_θ:_pres, {be_θ, planes}} INFL_v:_pl

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they [gray]

WS 3: {{they, {flying_θ, they}}, {v_be:_θ:_pres, {be_θ, planes}}} INFL_v:_pl

WS 4: {INFL_v:_pl, {{they, {flying_θ, they}}, {v_be:_θ:_pres, {be_θ, planes}}}}

Final WS: {C, {INFL_v:_pl, {{they, {flying_θ, they}}, {v_be:_θ:_pres, {be_θ, planes}}}}}

INT/EXT: {C, {INFL_v:_pl, {{they, {flying_θ, they}}, {v_be:_θ:_pres, {be_θ, planes}}}}}

EXT: flying they 3pl pres be planes

Spellout: flying they are planes

Blocked: inconsistent with input!

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they [gray]

WS 3: {they, {v_be:_θ:_pres, {be_θ, planes}}} flying_θ INFL_v:_pl

WS 4: {flying_θ, they} {they, {v_be:_θ:_pres, {be_θ, planes}}} INFL_v:_pl

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they [gray]

WS 3: {flying_θ, they} {v_be:_θ:_pres, {be_θ, planes}} INFL_v:_pl [gray]

WS 4: {flying_θ, planes} {they, {v_be:_θ:_pres, {be_θ, planes}}} INFL_v:_pl

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they [gray]

WS 3: {flying_θ, they} {v_be:_θ:_pres, {be_θ, planes}} INFL_v:_pl [gray]

WS 4: {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, planes}}}} flying_θ

WS 5: {flying_θ, they} {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, planes}}}}

WS 1: {be_θ, planes} flying_θ v_be:_θ:_pres INFL_v:_pl they

WS 2: {v_be:_θ:_pres, {be_θ, planes}} flying_θ INFL_v:_pl they [gray]

WS 3: {flying_θ, they} {v_be:_θ:_pres, {be_θ, planes}} INFL_v:_pl [gray]

WS 4: {flying_θ, they} {they, {v_be:_θ:_pres, {be_θ, planes}}} INFL_v:_pl [gray]

WS 5: {flying_θ, planes} {INFL_v:_pl, {they, {v_be:_θ:_pres, {be_θ, planes}}}}

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl

WS 3: {flying_θ, planes} {v_be:_θ:_pres, {be_θ, they}} INFL_v:_pl

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl [gray]

WS 3: {{planes, {flying_θ, planes}}, {v_be:_θ:_pres, {be_θ, they}}} INFL_v:_pl

WS 4: {INFL_v:_pl, {{planes, {flying_θ, planes}}, {v_be:_θ:_pres, {be_θ, they}}}}

Final WS: {C, {INFL_v:_pl, {{planes, {flying_θ, planes}}, {v_be:_θ:_pres, {be_θ, they}}}}}

INT/EXT: {C, {INFL_v:_pl, {{planes, {flying_θ, planes}}, {v_be:_θ:_pres, {be_θ, they}}}}}

Error: Case: object "they" not ACC

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl [gray]

WS 3: {planes, {v_be:_θ:_pres, {be_θ, they}}} flying_θ INFL_v:_pl

WS 4: {flying_θ, planes} {planes, {v_be:_θ:_pres, {be_θ, they}}} INFL_v:_pl

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl [gray]

WS 3: {flying_θ, planes} {v_be:_θ:_pres, {be_θ, they}} INFL_v:_pl [gray]

WS 4: {flying_θ, they} {planes, {v_be:_θ:_pres, {be_θ, they}}} INFL_v:_pl

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl [gray]

WS 3: {flying_θ, planes} {v_be:_θ:_pres, {be_θ, they}} INFL_v:_pl [gray]

WS 4: {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, they}}}} flying_θ

WS 5: {flying_θ, planes} {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, they}}}}

WS 1: {be_θ, they} planes flying_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {v_be:_θ:_pres, {be_θ, they}} planes flying_θ INFL_v:_pl [gray]

WS 3: {flying_θ, planes} {v_be:_θ:_pres, {be_θ, they}} INFL_v:_pl [gray]

WS 4: {flying_θ, planes} {planes, {v_be:_θ:_pres, {be_θ, they}}} INFL_v:_pl [gray]

WS 5: {flying_θ, they} {INFL_v:_pl, {planes, {v_be:_θ:_pres, {be_θ, they}}}}

WS 1: {planes, they} flying_θ be_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {flying_θ, {planes, they}} be_θ v_be:_θ:_pres INFL_v:_pl

WS 1: {planes, they} flying_θ be_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {be_θ, {planes, they}} flying_θ v_be:_θ:_pres INFL_v:_pl

WS 3: {v_be:_θ:_pres, {be_θ, {planes, they}}} flying_θ INFL_v:_pl

WS 4: {flying_θ, {planes, they}} {v_be:_θ:_pres, {be_θ, {planes, they}}} INFL_v:_pl

WS 1: {planes, they} flying_θ be_θ v_be:_θ:_pres INFL_v:_pl

WS 2: {flying_θ, {planes, they}} be_θ v_be:_θ:_pres INFL_v:_pl [gray]

WS 3: {v_be:_θ:_pres, {be_θ, {planes, they}}} flying_θ INFL_v:_pl [gray]

WS 4: {{planes, they}, {v_be:_θ:_pres, {be_θ, {planes, they}}}} flying_θ INFL_v:_pl

WS 5: {INFL_v:_pl, {{planes, they}, {v_be:_θ:_pres, {be_θ, {planes, they}}}}} flying_θ