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

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: colorless ideas sleep

Initial WS 1: sleep_ø v_sleep:_θ:_pres INFL_v ideas colorless_θ

WS 1: {colorless_θ, ideas} sleep_ø v_sleep:_θ:_pres INFL_v

WS 1: {v_sleep:_θ:_pres, sleep_ø} INFL_v ideas colorless_θ

WS 2: {colorless_θ, ideas} {v_sleep:_θ:_pres, sleep_ø} INFL_v

WS 1: {v_sleep:_θ:_pres, sleep_ø} INFL_v ideas colorless_θ

WS 2: {{ideas, {colorless_θ, ideas}}, {v_sleep:_θ:_pres, sleep_ø}} INFL_v

WS 3: {INFL_v, {{ideas, {colorless_θ, ideas}}, {v_sleep:_θ:_pres, sleep_ø}}}

Final WS: {C, {INFL_v, {{ideas, {colorless_θ, ideas}}, {v_sleep:_θ:_pres, sleep_ø}}}}

INT/EXT: {C, {INFL_v, {{ideas, {colorless_θ, ideas}}, {v_sleep:_θ:_pres, sleep_ø}}}}

EXT: colorless ideas 3pl pres sleep

Spellout: colorless ideas sleep

Parse found: colorless ideas 3pl pres sleep

WS 1: {v_sleep:_θ:_pres, sleep_ø} INFL_v ideas colorless_θ

WS 2: {ideas, {v_sleep:_θ:_pres, sleep_ø}} INFL_v colorless_θ

WS 3: {colorless_θ, ideas} {ideas, {v_sleep:_θ:_pres, sleep_ø}} INFL_v

WS 1: {v_sleep:_θ:_pres, sleep_ø} INFL_v ideas colorless_θ

WS 2: {colorless_θ, ideas} {v_sleep:_θ:_pres, sleep_ø} INFL_v [gray]

WS 3: {INFL_v, {ideas, {v_sleep:_θ:_pres, sleep_ø}}} colorless_θ

WS 4: {colorless_θ, ideas} {INFL_v, {ideas, {v_sleep:_θ:_pres, sleep_ø}}}